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Papers by Joseph Sarr

In West Africa, there is serious asymmetry on food safety between consumers and food producers. T... more In West Africa, there is serious asymmetry on food safety between consumers and food producers. This made that the management system of food safety in many developing countries became a top priority for authorities and decision makers. In Senegal, the government has selected the flood plain of Kayanga River to develop irrigated agriculture through rice cultivation to promote the food safety. For this, two dams (Niandouba and Confluent) have been built to reinforce water availability .The management of this hydraulic system required the better knowledge of its water resources through the dynamic of the flow. In this paper, we used Hec-ras model to compute the flow characteristics to analyze the hydraulic behavior of this system. The river reach selected, is located between the Niandouba dam and Kounkane threshold. From the DEM of this area, we have divided the river reach into 78 cross sections perpendicular to flow direction and numbered from 1 to 78. Arcgis software is used to extr...

Rеvuе des Energies Renouvelables, Mar 31, 2014

International Journal of Numerical Methods for Heat & Fluid Flow, 2009

PurposeThe purpose of this paper is to study the transient natural convection of a Newtonian flui... more PurposeThe purpose of this paper is to study the transient natural convection of a Newtonian fluid which develops in a closed spherical annulus delimited by two vertically eccentric spheres by using a bispherical coordinates system. The inner sphere is heated by a heat flux of constant density and the outer one is maintained isothermal.Design/methodology/approachThe transfer equations are written by using a bispherical coordinates system. The Navier‐Stokes equations are solved and coupled with the energy equation by using the alternating direction implicit (ADI) and the successive over relaxation (SOR) methods.FindingsThe study of the stream function and the Nusselt number shows that the convection motion is reinforced for the geometries characterized by positive values of the eccentricity with heat exchange increasing. The Nusselt number increases with the modified Rayleigh number. The heat exchange increases with the radius ratio. The results show that the steady state is reached ...

Open Journal of Fluid Dynamics

A numerical study is presented on the problem of 2D natural convection in a differentially heated... more A numerical study is presented on the problem of 2D natural convection in a differentially heated cavity. The equations governing this unsteady flow phenomenon were solved using the vorticity-stream function formulation of the Navier-Stokes equations and heat. The results obtained are compared with the results of the literature and make it possible to validate this approach. In this work, we studied the heat transfer in a cavity and we determined the variation of the local Nusselt number which allows obtaining the rate of thermal transfer by convection in an enclosure. We analyzed thermal fields for different Rayleigh numbers by selecting two points to visualize temperature fluctuations over time. Thus, the creation of the ascending and descending movements of the fluid inside the cavity was analyzed. We have also established temperature histograms for the graphical presentation of the temperature distribution. The modeling of the two-dimensional problem was established using a "Fortran 90" calculation code. The results also show the different vorticity contour maps in laminar flow regime. We have presented our results of numerical simulations using a visualization tool. The Rayleigh number varies in the range of 10³ to 10⁶ for a Prandtl number equal to 0.72 corresponding to air.

-Senegal is one of the developing countries and its dependence upon imported fossil fuels can onl... more -Senegal is one of the developing countries and its dependence upon imported fossil fuels can only be offset by the sustained exploitation of its indigenous resources. Wind energy is

… Journal of Physical …, 2009

This paper presents a performance analysis of a solar air collector with tilted side faces. The n... more This paper presents a performance analysis of a solar air collector with tilted side faces. The northern side wall is tilted at an angle of 38 and other walls are tilted at an angle of 9 relative to the vertical. All these walls are covered with a thin reflective aluminium film. The device ...

Open Journal of Applied Sciences, 2021

The subject of natural convection heat transfer is motivated by a wide range of applications in e... more The subject of natural convection heat transfer is motivated by a wide range of applications in engineering technology. The hemispherical cavity is a part of basic geometries although it is not widely studied. The effect of inclinaison on natural convection fluid motions in the gap between two eccentric hemispheres is numerically studied. The inner hemisphere is subjected to a heat flux of a constant density and the outer one is maintened isothermal. The walls separating the two hemispheres are thermally adiabatic. Equations are formulated with vorticity and stream-functions variables. It is also assumed the fluid incompressible and obeys the approximation of Boussinesq. These equations are written by using bispherical coordinates system and solved by using a finite difference method. The results show the topology of flow is strongly dependent on the inclinaison because the flow can change from a unicellular regime to a multicellular regime by varying the inclination from 0 to π. By...

Abstract: Using a bi-cylindrical coordinates system and a vorticity-stream function formulation, ... more Abstract: Using a bi-cylindrical coordinates system and a vorticity-stream function formulation, the authors study numerically the two dimensional unsteady natural convection of a Newtonian fluid bounded by portions of cylinders. A spatial discretization based on the finite difference method is used to approximate the dimensionless equations. While a purely implicit scheme is adopted for the time discretization. The algebraic systems of equations resulting from the discretization are solved by a Successive under Relaxation (SUR) method. The authors analyzed the effects of the Rayleigh number on the dynamic of the system. The analysis of the thermal and flow field showed that for Rayleigh number greater than 5.10 6 the transfers inside the enclosure are dominated by convection.

Open Journal of Applied Sciences, 2021

The subject of natural convection heat transfer is motivated by a wide range of applications in e... more The subject of natural convection heat transfer is motivated by a wide range of applications in engineering technology. The hemispherical cavity is a part of basic geometries although it is not widely studied. The effect of inclinaison on natural convection fluid motions in the gap between two eccentric hemispheres is numerically studied. The inner hemisphere is subjected to a heat flux of a constant density and the outer one is maintened isothermal. The walls separating the two hemispheres are thermally adiabatic. Equations are formulated with vorticity and stream-functions variables. It is also assumed the fluid incompressible and obeys the approximation of Boussinesq. These equations are written by using bispherical coordinates system and solved by using a finite difference method. The results show the topology of flow is strongly dependent on the inclinaison because the flow can change from a unicellular regime to a multicellular regime by varying the inclination from 0 to π. By...

Open Journal of Applied Sciences, 2021

Natural convection heat transfer in open or closed cavities takes place in different engineering ... more Natural convection heat transfer in open or closed cavities takes place in different engineering areas. The hemispherical cavity is a part of basic geometries although it is not widely studied. The present paper reports the numerical study of natural convection in a closed hemispherical annulus delimited by two vertically eccentric hemispheres filled with Newtonian fluid (air in this case with Pr = 0.7) is conducted. The inner hemisphere is heated by a heat flux of constant density and the outer one is maintained isothermal. Based on the Boussinesq assumptions, the governing equations are numerically studied using unsteady natural convection formulated with vorticity and stream-function variables. These equations are written by using bispherical coordinates system and solved by using a finite difference method. The effect of the control parameters such as the Rayleigh number (103 ≤ Ra ≤ 106) or the eccentricity (e = ±0.2, ±0.5, 0) in the dynamic and thermal behaviours of the fluid i...

This paper attempts to analyze spatial variability, temporal trends and identify the discontinuit... more This paper attempts to analyze spatial variability, temporal trends and identify the discontinuities in the maximum and minimum temperature’s time series. This study is based on annual and monthly data from the Kolda Weather Station over a 50-year period. Our approach is essentially structured according to 3 components: first, anomaly index and cumulative sums are calculated and finally, Mann-Kendall statistical test is performed. Considering anomaly index, results highlight four categories of periods both annual and monthly scale: very hot, hot, very cold and cold for the maximums and the minimums. The analysis indicated that minimums increased significantly more than maximums. Regarding the CUSUM, results showed a downward trend for maximums and upwards for minimums on an annual and monthly basis. The dates of these breaks are 2001 and May for maximums and 1975 and February for minimums respectively at annual and monthly scale . Regarding Mann Kendall test, results show a signific...

A numerical study of the forced condensation in a pure saturated steam and to a vertical wall cov... more A numerical study of the forced condensation in a pure saturated steam and to a vertical wall covered with a porous material are brought convection. The transfer in the liquid medium and the porous film are disclosed respectively by the Darcy-Brinkman model and conventional equations for the boundary layer. The dimensionless equations are solved by an implicit finite difference method combined with an iterative method like Gauss-Seidel. The film thickness of the condensate is determined from the heat balance equation of the liquid vapor interface is solved by an iterative procedure. We analyze the influence of Reynolds and Jacob numbers, the dimensionless thickness of the porous layer and the non-dimensional thermal conductivity transfers in the liquid phase

Spatial monitoring of climate behavior through rainfall variability is important step for the bet... more Spatial monitoring of climate behavior through rainfall variability is important step for the better understanding of the water resources in the river system. This paper aims to highlight rainfall variability at yearly scale and identify the various climate situations and characteristics of the study area during studied chronicle in the lower valley of the Casamance river basin. Three rainfall stations Ziguinchor, Bignona and Oussouye over the period of 55 years on average acquiring from ANACIM database (National Agency of Civil Aviation and Meteorology), have been selected for this purpose. Choice of rainfall is due to the fact that it is a key variable in West Africa in general and more specifically over the Sahel region where economies, livelihoods and food security are highly dependent on rained agriculture. To reach our objective, we have proceded through some analysis based on rupture detection testing (Pettitt, Hubert, Buishand and Lee and Heghinian test) and randomness testi...

In West Africa, there is serious asymmetry on food safety between consumers and food producers. T... more In West Africa, there is serious asymmetry on food safety between consumers and food producers. This made that the management system of food safety in many developing countries became a top priority for authorities and decision makers. In Senegal, the government has selected the flood plain of Kayanga River to develop irrigated agriculture through rice cultivation to promote the food safety. For this, two dams (Niandouba and Confluent) have been built to reinforce water availability .The management of this hydraulic system required the better knowledge of its water resources through the dynamic of the flow. In this paper, we used Hec-ras model to compute the flow characteristics to analyze the hydraulic behavior of this system. The river reach selected, is located between the Niandouba dam and Kounkane threshold. From the DEM of this area, we have divided the river reach into 78 cross sections perpendicular to flow direction and numbered from 1 to 78. Arcgis software is used to extr...

L'auteur a etudie la convection naturelle symetrique dans une enceinte fermee limitee par deu... more L'auteur a etudie la convection naturelle symetrique dans une enceinte fermee limitee par deux cylindres concentriques horizontaux et deux plans diametraux. La paroi cylindrique interieure est soumise a un flux de densite constante alors que la paroi cylindrique exterieure est maintenue a une temperature constante et les parois laterales isolees. Pour faciliter la mise en equations du probleme, l'auteur a transforme ce domaine curviligne en rectangle a l'aide d'une tranformation conforme appropriee. Il a ensuite etudie les transferts thermiques en fonction des nombres de grashof modifies et des facteurs de forme. Les resultats montrent que les echanges thermo-convectifs au niveau des parois actives sont meilleurs quand on augmente le facteur de forme et que la limite superieure du regime conductif dominant est atteint pour un nombre de grashof d'environ 1000. Les resultats theoriques ont ete valides par une methode experimentale d'interferometrie holographique.

Open Journal of Fluid Dynamics, 2017

In this present work, we study heat transfer in a confined environment. We have to determine the ... more In this present work, we study heat transfer in a confined environment. We have to determine the thermal and dynamics fields of the cavity while observing the effect of the Rayleigh number which depends on the characteristics of the fluid and the temperatures imposed. The behavior of boundary layers in natural convection is analyzed along this square cavity. The central halves of its vertical walls are heated at different temperatures. The left active part is at a higher temperature than the one on the right wall. The remaining inactive parts and the horizontal walls (upper and lower) are adiabatic. The thermal and dynamic modeling of two-dimensional problem was done using a calculation code Fortran 90 and a visualization software ParaView based on the finite volume method. The equations governing this phenomenon of unsteady flow have thus been solved. This allows the modeling of both air flow and heat transfer with a numerical stabilization of the solution. So, we have presented our results of numerical simulations using a visualization tool. The results show the different velocity and temperature curves, velocity vectors and isotherms in laminar flow regime.

Journal of Heat Transfer, 1995

The two-dimensional heat transfer induced by free laminar convection in an enclosure is numerical... more The two-dimensional heat transfer induced by free laminar convection in an enclosure is numerically investigated in this work. A constant wall heat flux is applied on the inner cylinder while the outer is maintained at an uniform temperature, the others walls being adiabatic. The influence of the modified Grashof number (102 ≤ Gr ≤ 106) and an aspect Fr on convective motion and heat transfer is examined. A comparison of the heat transfer between different fluids such as air, ammonia–liquid, and carbon dioxide–liquid is also displayed. Holographic interferometry is used to visualize the temperature field within the enclosure and to confirm the two-dimensional behavior of the convective flow. The results show that maximum heat transfer is found for Fr = 1, when the Grashof number is up to 103, and the conduction regime is reached for a modified Grashof number less than 103. On the other hand, the average Nusselt number increases with the Prandtl number, Fr = 1.

Open Journal of Fluid Dynamics

A numerical study is presented on the problem of 2D natural convection in a differentially heated... more A numerical study is presented on the problem of 2D natural convection in a differentially heated cavity. The equations governing this unsteady flow phenomenon were solved using the vorticity-stream function formulation of the Navier-Stokes equations and heat. The results obtained are compared with the results of the literature and make it possible to validate this approach. In this work, we studied the heat transfer in a cavity and we determined the variation of the local Nusselt number which allows obtaining the rate of thermal transfer by convection in an enclosure. We analyzed thermal fields for different Rayleigh numbers by selecting two points to visualize temperature fluctuations over time. Thus, the creation of the ascending and descending movements of the fluid inside the cavity was analyzed. We have also established temperature histograms for the graphical presentation of the temperature distribution. The modeling of the two-dimensional problem was established using a "Fortran 90" calculation code. The results also show the different vorticity contour maps in laminar flow regime. We have presented our results of numerical simulations using a visualization tool. The Rayleigh number varies in the range of 10³ to 10⁶ for a Prandtl number equal to 0.72 corresponding to air.

Research Journal of Applied Sciences, Engineering and Technology, 2014

In West Africa, there is serious asymmetry on food safety between consumers and food producers. T... more In West Africa, there is serious asymmetry on food safety between consumers and food producers. This made that the management system of food safety in many developing countries became a top priority for authorities and decision makers. In Senegal, the government has selected the flood plain of Kayanga River to develop irrigated agriculture through rice cultivation to promote the food safety. For this, two dams (Niandouba and Confluent) have been built to reinforce water availability .The management of this hydraulic system required the better knowledge of its water resources through the dynamic of the flow. In this paper, we used Hec-ras model to compute the flow characteristics to analyze the hydraulic behavior of this system. The river reach selected, is located between the Niandouba dam and Kounkane threshold. From the DEM of this area, we have divided the river reach into 78 cross sections perpendicular to flow direction and numbered from 1 to 78. Arcgis software is used to extr...

Rеvuе des Energies Renouvelables, Mar 31, 2014

International Journal of Numerical Methods for Heat & Fluid Flow, 2009

PurposeThe purpose of this paper is to study the transient natural convection of a Newtonian flui... more PurposeThe purpose of this paper is to study the transient natural convection of a Newtonian fluid which develops in a closed spherical annulus delimited by two vertically eccentric spheres by using a bispherical coordinates system. The inner sphere is heated by a heat flux of constant density and the outer one is maintained isothermal.Design/methodology/approachThe transfer equations are written by using a bispherical coordinates system. The Navier‐Stokes equations are solved and coupled with the energy equation by using the alternating direction implicit (ADI) and the successive over relaxation (SOR) methods.FindingsThe study of the stream function and the Nusselt number shows that the convection motion is reinforced for the geometries characterized by positive values of the eccentricity with heat exchange increasing. The Nusselt number increases with the modified Rayleigh number. The heat exchange increases with the radius ratio. The results show that the steady state is reached ...

Open Journal of Fluid Dynamics

A numerical study is presented on the problem of 2D natural convection in a differentially heated... more A numerical study is presented on the problem of 2D natural convection in a differentially heated cavity. The equations governing this unsteady flow phenomenon were solved using the vorticity-stream function formulation of the Navier-Stokes equations and heat. The results obtained are compared with the results of the literature and make it possible to validate this approach. In this work, we studied the heat transfer in a cavity and we determined the variation of the local Nusselt number which allows obtaining the rate of thermal transfer by convection in an enclosure. We analyzed thermal fields for different Rayleigh numbers by selecting two points to visualize temperature fluctuations over time. Thus, the creation of the ascending and descending movements of the fluid inside the cavity was analyzed. We have also established temperature histograms for the graphical presentation of the temperature distribution. The modeling of the two-dimensional problem was established using a "Fortran 90" calculation code. The results also show the different vorticity contour maps in laminar flow regime. We have presented our results of numerical simulations using a visualization tool. The Rayleigh number varies in the range of 10³ to 10⁶ for a Prandtl number equal to 0.72 corresponding to air.

-Senegal is one of the developing countries and its dependence upon imported fossil fuels can onl... more -Senegal is one of the developing countries and its dependence upon imported fossil fuels can only be offset by the sustained exploitation of its indigenous resources. Wind energy is

… Journal of Physical …, 2009

This paper presents a performance analysis of a solar air collector with tilted side faces. The n... more This paper presents a performance analysis of a solar air collector with tilted side faces. The northern side wall is tilted at an angle of 38 and other walls are tilted at an angle of 9 relative to the vertical. All these walls are covered with a thin reflective aluminium film. The device ...

Open Journal of Applied Sciences, 2021

The subject of natural convection heat transfer is motivated by a wide range of applications in e... more The subject of natural convection heat transfer is motivated by a wide range of applications in engineering technology. The hemispherical cavity is a part of basic geometries although it is not widely studied. The effect of inclinaison on natural convection fluid motions in the gap between two eccentric hemispheres is numerically studied. The inner hemisphere is subjected to a heat flux of a constant density and the outer one is maintened isothermal. The walls separating the two hemispheres are thermally adiabatic. Equations are formulated with vorticity and stream-functions variables. It is also assumed the fluid incompressible and obeys the approximation of Boussinesq. These equations are written by using bispherical coordinates system and solved by using a finite difference method. The results show the topology of flow is strongly dependent on the inclinaison because the flow can change from a unicellular regime to a multicellular regime by varying the inclination from 0 to π. By...

Abstract: Using a bi-cylindrical coordinates system and a vorticity-stream function formulation, ... more Abstract: Using a bi-cylindrical coordinates system and a vorticity-stream function formulation, the authors study numerically the two dimensional unsteady natural convection of a Newtonian fluid bounded by portions of cylinders. A spatial discretization based on the finite difference method is used to approximate the dimensionless equations. While a purely implicit scheme is adopted for the time discretization. The algebraic systems of equations resulting from the discretization are solved by a Successive under Relaxation (SUR) method. The authors analyzed the effects of the Rayleigh number on the dynamic of the system. The analysis of the thermal and flow field showed that for Rayleigh number greater than 5.10 6 the transfers inside the enclosure are dominated by convection.

Open Journal of Applied Sciences, 2021

The subject of natural convection heat transfer is motivated by a wide range of applications in e... more The subject of natural convection heat transfer is motivated by a wide range of applications in engineering technology. The hemispherical cavity is a part of basic geometries although it is not widely studied. The effect of inclinaison on natural convection fluid motions in the gap between two eccentric hemispheres is numerically studied. The inner hemisphere is subjected to a heat flux of a constant density and the outer one is maintened isothermal. The walls separating the two hemispheres are thermally adiabatic. Equations are formulated with vorticity and stream-functions variables. It is also assumed the fluid incompressible and obeys the approximation of Boussinesq. These equations are written by using bispherical coordinates system and solved by using a finite difference method. The results show the topology of flow is strongly dependent on the inclinaison because the flow can change from a unicellular regime to a multicellular regime by varying the inclination from 0 to π. By...

Open Journal of Applied Sciences, 2021

Natural convection heat transfer in open or closed cavities takes place in different engineering ... more Natural convection heat transfer in open or closed cavities takes place in different engineering areas. The hemispherical cavity is a part of basic geometries although it is not widely studied. The present paper reports the numerical study of natural convection in a closed hemispherical annulus delimited by two vertically eccentric hemispheres filled with Newtonian fluid (air in this case with Pr = 0.7) is conducted. The inner hemisphere is heated by a heat flux of constant density and the outer one is maintained isothermal. Based on the Boussinesq assumptions, the governing equations are numerically studied using unsteady natural convection formulated with vorticity and stream-function variables. These equations are written by using bispherical coordinates system and solved by using a finite difference method. The effect of the control parameters such as the Rayleigh number (103 ≤ Ra ≤ 106) or the eccentricity (e = ±0.2, ±0.5, 0) in the dynamic and thermal behaviours of the fluid i...

This paper attempts to analyze spatial variability, temporal trends and identify the discontinuit... more This paper attempts to analyze spatial variability, temporal trends and identify the discontinuities in the maximum and minimum temperature’s time series. This study is based on annual and monthly data from the Kolda Weather Station over a 50-year period. Our approach is essentially structured according to 3 components: first, anomaly index and cumulative sums are calculated and finally, Mann-Kendall statistical test is performed. Considering anomaly index, results highlight four categories of periods both annual and monthly scale: very hot, hot, very cold and cold for the maximums and the minimums. The analysis indicated that minimums increased significantly more than maximums. Regarding the CUSUM, results showed a downward trend for maximums and upwards for minimums on an annual and monthly basis. The dates of these breaks are 2001 and May for maximums and 1975 and February for minimums respectively at annual and monthly scale . Regarding Mann Kendall test, results show a signific...

A numerical study of the forced condensation in a pure saturated steam and to a vertical wall cov... more A numerical study of the forced condensation in a pure saturated steam and to a vertical wall covered with a porous material are brought convection. The transfer in the liquid medium and the porous film are disclosed respectively by the Darcy-Brinkman model and conventional equations for the boundary layer. The dimensionless equations are solved by an implicit finite difference method combined with an iterative method like Gauss-Seidel. The film thickness of the condensate is determined from the heat balance equation of the liquid vapor interface is solved by an iterative procedure. We analyze the influence of Reynolds and Jacob numbers, the dimensionless thickness of the porous layer and the non-dimensional thermal conductivity transfers in the liquid phase

Spatial monitoring of climate behavior through rainfall variability is important step for the bet... more Spatial monitoring of climate behavior through rainfall variability is important step for the better understanding of the water resources in the river system. This paper aims to highlight rainfall variability at yearly scale and identify the various climate situations and characteristics of the study area during studied chronicle in the lower valley of the Casamance river basin. Three rainfall stations Ziguinchor, Bignona and Oussouye over the period of 55 years on average acquiring from ANACIM database (National Agency of Civil Aviation and Meteorology), have been selected for this purpose. Choice of rainfall is due to the fact that it is a key variable in West Africa in general and more specifically over the Sahel region where economies, livelihoods and food security are highly dependent on rained agriculture. To reach our objective, we have proceded through some analysis based on rupture detection testing (Pettitt, Hubert, Buishand and Lee and Heghinian test) and randomness testi...

In West Africa, there is serious asymmetry on food safety between consumers and food producers. T... more In West Africa, there is serious asymmetry on food safety between consumers and food producers. This made that the management system of food safety in many developing countries became a top priority for authorities and decision makers. In Senegal, the government has selected the flood plain of Kayanga River to develop irrigated agriculture through rice cultivation to promote the food safety. For this, two dams (Niandouba and Confluent) have been built to reinforce water availability .The management of this hydraulic system required the better knowledge of its water resources through the dynamic of the flow. In this paper, we used Hec-ras model to compute the flow characteristics to analyze the hydraulic behavior of this system. The river reach selected, is located between the Niandouba dam and Kounkane threshold. From the DEM of this area, we have divided the river reach into 78 cross sections perpendicular to flow direction and numbered from 1 to 78. Arcgis software is used to extr...

L'auteur a etudie la convection naturelle symetrique dans une enceinte fermee limitee par deu... more L'auteur a etudie la convection naturelle symetrique dans une enceinte fermee limitee par deux cylindres concentriques horizontaux et deux plans diametraux. La paroi cylindrique interieure est soumise a un flux de densite constante alors que la paroi cylindrique exterieure est maintenue a une temperature constante et les parois laterales isolees. Pour faciliter la mise en equations du probleme, l'auteur a transforme ce domaine curviligne en rectangle a l'aide d'une tranformation conforme appropriee. Il a ensuite etudie les transferts thermiques en fonction des nombres de grashof modifies et des facteurs de forme. Les resultats montrent que les echanges thermo-convectifs au niveau des parois actives sont meilleurs quand on augmente le facteur de forme et que la limite superieure du regime conductif dominant est atteint pour un nombre de grashof d'environ 1000. Les resultats theoriques ont ete valides par une methode experimentale d'interferometrie holographique.

Open Journal of Fluid Dynamics, 2017

In this present work, we study heat transfer in a confined environment. We have to determine the ... more In this present work, we study heat transfer in a confined environment. We have to determine the thermal and dynamics fields of the cavity while observing the effect of the Rayleigh number which depends on the characteristics of the fluid and the temperatures imposed. The behavior of boundary layers in natural convection is analyzed along this square cavity. The central halves of its vertical walls are heated at different temperatures. The left active part is at a higher temperature than the one on the right wall. The remaining inactive parts and the horizontal walls (upper and lower) are adiabatic. The thermal and dynamic modeling of two-dimensional problem was done using a calculation code Fortran 90 and a visualization software ParaView based on the finite volume method. The equations governing this phenomenon of unsteady flow have thus been solved. This allows the modeling of both air flow and heat transfer with a numerical stabilization of the solution. So, we have presented our results of numerical simulations using a visualization tool. The results show the different velocity and temperature curves, velocity vectors and isotherms in laminar flow regime.

Journal of Heat Transfer, 1995

The two-dimensional heat transfer induced by free laminar convection in an enclosure is numerical... more The two-dimensional heat transfer induced by free laminar convection in an enclosure is numerically investigated in this work. A constant wall heat flux is applied on the inner cylinder while the outer is maintained at an uniform temperature, the others walls being adiabatic. The influence of the modified Grashof number (102 ≤ Gr ≤ 106) and an aspect Fr on convective motion and heat transfer is examined. A comparison of the heat transfer between different fluids such as air, ammonia–liquid, and carbon dioxide–liquid is also displayed. Holographic interferometry is used to visualize the temperature field within the enclosure and to confirm the two-dimensional behavior of the convective flow. The results show that maximum heat transfer is found for Fr = 1, when the Grashof number is up to 103, and the conduction regime is reached for a modified Grashof number less than 103. On the other hand, the average Nusselt number increases with the Prandtl number, Fr = 1.

Open Journal of Fluid Dynamics

A numerical study is presented on the problem of 2D natural convection in a differentially heated... more A numerical study is presented on the problem of 2D natural convection in a differentially heated cavity. The equations governing this unsteady flow phenomenon were solved using the vorticity-stream function formulation of the Navier-Stokes equations and heat. The results obtained are compared with the results of the literature and make it possible to validate this approach. In this work, we studied the heat transfer in a cavity and we determined the variation of the local Nusselt number which allows obtaining the rate of thermal transfer by convection in an enclosure. We analyzed thermal fields for different Rayleigh numbers by selecting two points to visualize temperature fluctuations over time. Thus, the creation of the ascending and descending movements of the fluid inside the cavity was analyzed. We have also established temperature histograms for the graphical presentation of the temperature distribution. The modeling of the two-dimensional problem was established using a "Fortran 90" calculation code. The results also show the different vorticity contour maps in laminar flow regime. We have presented our results of numerical simulations using a visualization tool. The Rayleigh number varies in the range of 10³ to 10⁶ for a Prandtl number equal to 0.72 corresponding to air.

Research Journal of Applied Sciences, Engineering and Technology, 2014