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Papers by Uthai Prasopchingchana

The Proceedings of the International Conference on Nuclear Engineering (ICONE)

World Academy of Science, Engineering and Technology, International Journal of Aerospace and Mechanical Engineering, Aug 25, 2016

Journal of Mechanical Engineering, Jan 15, 2021

This paper proposes a novel extrapolation method known as the Lagrange polynomial interpolation w... more This paper proposes a novel extrapolation method known as the Lagrange polynomial interpolation with weighting factors (LPI-WF) to determine initial guess values in each time step for solving equation systems of transient problems using iterative methods. The LPI-WF method is developed from the Lagrange polynomial interpolation to determine the direct extrapolation values and multiply them with the weighting factors. The weighting factors are calculated by considering the number of the previous time steps involved in the extrapolation and the duration between the present time step and the previous time steps. Thus, the LPI-WF method is proper for use with highorder temporal schemes. The key advantages of the LPI-WF method are that the computational time required to achieve the steady-state condition of the transient problems is reduced and the computation codes with the LPI-WF method is more stable than without the LPI-WF method at high time step values. A performance test of the LPI-WF method is carried out by comparing the computational time based on the "lid-driven cavity flow" problem for Reynolds numbers of 1000 and 5000. The test result shows that the computational time of the problem when the LPI-WF method is adopted can be reduced up to 10.46 % compared to the conventional method.

Volume 10: Heat Transfer, Fluid Flows, and Thermal Systems, Parts A, B, and C, 2008

Numerical simulations of heat and mass transfer in supercritical carbon dioxide are carried out f... more Numerical simulations of heat and mass transfer in supercritical carbon dioxide are carried out for natural convection conditions in a differentially heated square enclosure. The two vertical walls are maintained at different temperatures while the two horizontal walls are insulated. For the mass transfer studies, a heated vertical naphthalene wall is considered. Properties of supercritical carbon dioxide are evaluated from the National Institute of Standards and Technology (NIST) Standard Reference Database 12. A correlation for the mean Nusselt number along the heated wall is obtained as a function of the heat transfer Rayleigh number (for a given Prandtl number). A correlation for the temporal Sherwood number along the naphthalene surface is obtained as a function of the mass transfer Rayleigh number, and Fourier number (for a given Schmidt number). The results are compared with result available in the literature.Copyright © 2008 by ASME

Journal of Mechanical Engineering

This paper proposes a novel extrapolation method known as the Lagrange polynomial interpolation w... more This paper proposes a novel extrapolation method known as the Lagrange polynomial interpolation with weighting factors (LPI-WF) to determine initial guess values in each time step for solving equation systems of transient problems using iterative methods. The LPI-WF method is developed from the Lagrange polynomial interpolation to determine the direct extrapolation values and multiply them with the weighting factors. The weighting factors are calculated by considering the number of the previous time steps involved in the extrapolation and the duration between the present time step and the previous time steps. Thus, the LPI-WF method is proper for use with highorder temporal schemes. The key advantages of the LPI-WF method are that the computational time required to achieve the steady-state condition of the transient problems is reduced and the computation codes with the LPI-WF method is more stable than without the LPI-WF method at high time step values. A performance test of the LP...

Universiti Teknologi MARA, 2021

This paper proposes a novel extrapolation method known as the Lagrange polynomial interpolation w... more This paper proposes a novel extrapolation method known as the Lagrange polynomial interpolation with weighting factors (LPI-WF) to determine initial guess values in each time step for solving equation systems of transient problems using iterative methods. The LPI-WF method is developed from the Lagrange polynomial interpolation to determine the direct extrapolation values and multiply them with the weighting factors. The weighting factors are calculated by considering the number of the previous time steps involved in the extrapolation and the duration between the present time step and the previous time steps. Thus, the LPI-WF method is proper for use with highorder temporal schemes. The key advantages of the LPI-WF method are that the computational time required to achieve the steady-state condition of the transient problems is reduced and the computation codes with the LPI-WF method is more stable than without the LPI-WF method at high time step values. A performance test of the LPI-WF method is carried out by comparing the computational time based on the "lid-driven cavity flow" problem for Reynolds numbers of 1000 and 5000. The test result shows that the computational time of the problem when the LPI-WF method is adopted can be reduced up to 10.46 % compared to the conventional method.

The temperature distribution and the heat transfer rates through a multi-layer door of a furnace ... more The temperature distribution and the heat transfer rates through a multi-layer door of a furnace were investigated. The inside of the door was in contact with hot air and the other side of the door was in contact with room air. Radiation heat transfer from the walls of the furnace to the door and the door to the surrounding area was included in the problem. This work is a two dimensional steady state problem. The Churchill and Chu correlation was used to find local convection heat transfer coefficients at the surfaces of the furnace door. The thermophysical properties of air were the functions of the temperatures. Polynomial curve fitting for the fluid properties were carried out. Finite difference method was used to discretize for conduction heat transfer within the furnace door. The Gauss-Seidel Iteration was employed to compute the temperature distribution in the door. The temperature distribution in the horizontal mid plane of the furnace door in a two dimensional problem agrees...

The objective of this article is to present the determination of the heat transfer rates through ... more The objective of this article is to present the determination of the heat transfer rates through a straight rectangular fin by the numerical method in 3 dimensions. The energy balance method is employed to determine the finite difference equations. The solutions of the equations are determined by the Gauss-Seidel iteration. Thermal radiation between the fin surfaces and the surrounding is concerned in the calculation and the local convection heat transfer coefficients are used in the calculation. The calculation is calculated under the steady-state condition and the constant temperature at the base of the fin condition. The results obtained from the calculation by the numerical method in 3 dimensions gained the values

World Academy of Science, Engineering and Technology, International Journal of Aerospace and Mechanical Engineering, 2016

IOP Conference Series: Materials Science and Engineering, 2019

Effects of cavity aspect ratios and cavity inclination angles to natural convection in a rectangu... more Effects of cavity aspect ratios and cavity inclination angles to natural convection in a rectangular cavity are numerically investigated. Investigation is performed at the Rayleigh number (Ra) equal to 104, the cavity aspect ratios from 1 to 50 and the cavity inclination angles from 0 to 180°. Consequently, Heat transfer enhancement or decreasing due to the effects is exposed. In addition, streamline contours in the rectangular cavity are illustrated. Multi-cellular flow figuring on the appropriate conditions is exhibited. A new correlation of the average Nusselt number, the cavity aspect ratio and the cavity inclination angle is formulated at Ra equal to 104.

International Journal of Materials, Mechanics and Manufacturing, 2013

Natural convection of air in an inclined square enclosure was numerically investigated. The left ... more Natural convection of air in an inclined square enclosure was numerically investigated. The left and right walls of the enclosure were maintained at the uniform hot and cold temperatures, respectively, while the top and bottom walls were adiabatic. The enclosure was filled with real air, a compressible Newtonian fluid. The finite volume method was employed to discretize the partial differential equations of airflow in the enclosure. The angles of the inclination of a square enclosure giving the maximum average Nusselt numbers are   110 o for Ra = 110 3 and   130 o for 310 3  Ra 110 4 .

International Journal of Thermal Sciences, Feb 1, 2022

Abstract Direct numerical simulation (DNS) is a powerful research technique to solve the Navier–S... more Abstract Direct numerical simulation (DNS) is a powerful research technique to solve the Navier–Stokes equations based on turbulent flows. DNS delivers highly reliable physical solutions with extreme accuracy. Unfortunately, present hardware and computing technologies remain limited, making it difficult to implement DNS in practice. The recently proposed Lagrange interpolating polynomial (LIP) scheme is a discretization technique for the finite-volume method. The LIP scheme is easy to use with nonuniform grid simulations and can flexibly increase or decrease the order of accuracy. The objective of this study is to verify that the LIP scheme is suitable for DNS of natural convection in a square cavity at high Rayleigh numbers (Ra). Accordingly, code was developed in-house using a second-order LIP scheme with the finite-volume method and the semi-implicit method for pressure-linked equations (SIMPLE) algorithm. Simulations were performed at Ra values of 109 and 1.58 × 109. The solutions were then verified against experimental benchmark data and published numerical solutions. The maximum differences in the Nusselt numbers between the computed solutions and the experimental benchmark data and published numerical solutions are 19.23% and 5.51%, respectively. However, the comparison results indicate that most of the computed solutions are in good agreement with experimental benchmark data and published numerical solutions.

IOP Conference Series: Materials Science and Engineering, 2021

Solution differences of natural convection in a tall cavity filled with air in which the density ... more Solution differences of natural convection in a tall cavity filled with air in which the density of the body force term are approximated by using the Boussinesq approximation (BA) and by using the real air density equation (RE) are numerically investigated. The main parameters for the investigation are Nusselt numbers and numbers of cells in the multi-cellular flow. The investigation is carried out for the Rayleigh number of 104, and the cavity aspect ratio equal to 60. The temperature differences of the vertical cavity walls are varied from 1 K to 200 K. These conditions are appropriate to form the multi-cellular flow in the tall cavity obviously, and close to the boundary of the laminar and turbulent flows. Consequently, the differences in both Nusselt numbers and numbers of the cells in the multi-cellular flow can be easily observed. The finite volume method with the Lagrange interpolating polynomial (LIP) scheme are selected to discretize the governing equations of the flow, and...

MATEC Web of Conferences, 2017

Modification of the Lagrange interpolating polynomial (LIP) scheme for using with the finite diff... more Modification of the Lagrange interpolating polynomial (LIP) scheme for using with the finite difference method is proposed. Merits of the modified LIP scheme used with the finite difference method for problem solving are facile to discretize equations, and fast to obtain solutions. Verification of the modified LIP scheme was performed by comparison of the solutions computed from the modified LIP scheme with the analytical solutions of a heat conduction problem. The verification gives credence to the modified LIP scheme for correctness of the solutions. In addition, the comparison results of solution accuracy and computational time of problem solving between using of the finite difference method with the modified LIP scheme and the finite volume method with the LIP scheme are exhibited. Recently, the Lagrange interpolating polynomial (LIP) scheme for using with the FVM was proposed by Prasopchingchana and Manewattana [7]. The LIP scheme is easily modified for using with the FDM, called the modified LIP scheme. An aim of this article is to propose a modified LIP scheme for using with the FDM. The modified LIP scheme is a high-order scheme used for discretization of the first and second derivatives of variables with respect to both space and time. Using the modified LIP scheme with the FDM to solve problems simulated by using non-uniform grids is facile, and solution convergence of the using is fast.

International Journal of Thermal Sciences

Engineering Journal

A new scheme applied to the finite volume method for solving the partial differential equations o... more A new scheme applied to the finite volume method for solving the partial differential equations of fluid flow is proposed. The Lagrange interpolating polynomial with a setting of zero for the spatial domain at the cell faces, and the present time at the cell center is adopted for the new scheme to estimate the values of the variables at the cell faces, the derivative values of the variables with respect to the spatial domain at the cell faces and the derivative values of the variables with respect to time at the cell center for spatial and temporal discretization of the discretized equation. The new scheme was verified by comparing the solutions of the new scheme to the benchmark numerical solutions and the published numerical solutions of two dimensional laminar natural convection in a square cavity. From the comparison, the results show that the solutions of the new scheme agree well with the benchmark numerical solutions and the published numerical solutions.

The Proceedings of the International Conference on Nuclear Engineering (ICONE)

World Academy of Science, Engineering and Technology, International Journal of Aerospace and Mechanical Engineering, Aug 25, 2016

Journal of Mechanical Engineering, Jan 15, 2021

This paper proposes a novel extrapolation method known as the Lagrange polynomial interpolation w... more This paper proposes a novel extrapolation method known as the Lagrange polynomial interpolation with weighting factors (LPI-WF) to determine initial guess values in each time step for solving equation systems of transient problems using iterative methods. The LPI-WF method is developed from the Lagrange polynomial interpolation to determine the direct extrapolation values and multiply them with the weighting factors. The weighting factors are calculated by considering the number of the previous time steps involved in the extrapolation and the duration between the present time step and the previous time steps. Thus, the LPI-WF method is proper for use with highorder temporal schemes. The key advantages of the LPI-WF method are that the computational time required to achieve the steady-state condition of the transient problems is reduced and the computation codes with the LPI-WF method is more stable than without the LPI-WF method at high time step values. A performance test of the LPI-WF method is carried out by comparing the computational time based on the "lid-driven cavity flow" problem for Reynolds numbers of 1000 and 5000. The test result shows that the computational time of the problem when the LPI-WF method is adopted can be reduced up to 10.46 % compared to the conventional method.

Volume 10: Heat Transfer, Fluid Flows, and Thermal Systems, Parts A, B, and C, 2008

Numerical simulations of heat and mass transfer in supercritical carbon dioxide are carried out f... more Numerical simulations of heat and mass transfer in supercritical carbon dioxide are carried out for natural convection conditions in a differentially heated square enclosure. The two vertical walls are maintained at different temperatures while the two horizontal walls are insulated. For the mass transfer studies, a heated vertical naphthalene wall is considered. Properties of supercritical carbon dioxide are evaluated from the National Institute of Standards and Technology (NIST) Standard Reference Database 12. A correlation for the mean Nusselt number along the heated wall is obtained as a function of the heat transfer Rayleigh number (for a given Prandtl number). A correlation for the temporal Sherwood number along the naphthalene surface is obtained as a function of the mass transfer Rayleigh number, and Fourier number (for a given Schmidt number). The results are compared with result available in the literature.Copyright © 2008 by ASME

Journal of Mechanical Engineering

This paper proposes a novel extrapolation method known as the Lagrange polynomial interpolation w... more This paper proposes a novel extrapolation method known as the Lagrange polynomial interpolation with weighting factors (LPI-WF) to determine initial guess values in each time step for solving equation systems of transient problems using iterative methods. The LPI-WF method is developed from the Lagrange polynomial interpolation to determine the direct extrapolation values and multiply them with the weighting factors. The weighting factors are calculated by considering the number of the previous time steps involved in the extrapolation and the duration between the present time step and the previous time steps. Thus, the LPI-WF method is proper for use with highorder temporal schemes. The key advantages of the LPI-WF method are that the computational time required to achieve the steady-state condition of the transient problems is reduced and the computation codes with the LPI-WF method is more stable than without the LPI-WF method at high time step values. A performance test of the LP...

Universiti Teknologi MARA, 2021

This paper proposes a novel extrapolation method known as the Lagrange polynomial interpolation w... more This paper proposes a novel extrapolation method known as the Lagrange polynomial interpolation with weighting factors (LPI-WF) to determine initial guess values in each time step for solving equation systems of transient problems using iterative methods. The LPI-WF method is developed from the Lagrange polynomial interpolation to determine the direct extrapolation values and multiply them with the weighting factors. The weighting factors are calculated by considering the number of the previous time steps involved in the extrapolation and the duration between the present time step and the previous time steps. Thus, the LPI-WF method is proper for use with highorder temporal schemes. The key advantages of the LPI-WF method are that the computational time required to achieve the steady-state condition of the transient problems is reduced and the computation codes with the LPI-WF method is more stable than without the LPI-WF method at high time step values. A performance test of the LPI-WF method is carried out by comparing the computational time based on the "lid-driven cavity flow" problem for Reynolds numbers of 1000 and 5000. The test result shows that the computational time of the problem when the LPI-WF method is adopted can be reduced up to 10.46 % compared to the conventional method.

The temperature distribution and the heat transfer rates through a multi-layer door of a furnace ... more The temperature distribution and the heat transfer rates through a multi-layer door of a furnace were investigated. The inside of the door was in contact with hot air and the other side of the door was in contact with room air. Radiation heat transfer from the walls of the furnace to the door and the door to the surrounding area was included in the problem. This work is a two dimensional steady state problem. The Churchill and Chu correlation was used to find local convection heat transfer coefficients at the surfaces of the furnace door. The thermophysical properties of air were the functions of the temperatures. Polynomial curve fitting for the fluid properties were carried out. Finite difference method was used to discretize for conduction heat transfer within the furnace door. The Gauss-Seidel Iteration was employed to compute the temperature distribution in the door. The temperature distribution in the horizontal mid plane of the furnace door in a two dimensional problem agrees...

The objective of this article is to present the determination of the heat transfer rates through ... more The objective of this article is to present the determination of the heat transfer rates through a straight rectangular fin by the numerical method in 3 dimensions. The energy balance method is employed to determine the finite difference equations. The solutions of the equations are determined by the Gauss-Seidel iteration. Thermal radiation between the fin surfaces and the surrounding is concerned in the calculation and the local convection heat transfer coefficients are used in the calculation. The calculation is calculated under the steady-state condition and the constant temperature at the base of the fin condition. The results obtained from the calculation by the numerical method in 3 dimensions gained the values

World Academy of Science, Engineering and Technology, International Journal of Aerospace and Mechanical Engineering, 2016

IOP Conference Series: Materials Science and Engineering, 2019

Effects of cavity aspect ratios and cavity inclination angles to natural convection in a rectangu... more Effects of cavity aspect ratios and cavity inclination angles to natural convection in a rectangular cavity are numerically investigated. Investigation is performed at the Rayleigh number (Ra) equal to 104, the cavity aspect ratios from 1 to 50 and the cavity inclination angles from 0 to 180°. Consequently, Heat transfer enhancement or decreasing due to the effects is exposed. In addition, streamline contours in the rectangular cavity are illustrated. Multi-cellular flow figuring on the appropriate conditions is exhibited. A new correlation of the average Nusselt number, the cavity aspect ratio and the cavity inclination angle is formulated at Ra equal to 104.

International Journal of Materials, Mechanics and Manufacturing, 2013

Natural convection of air in an inclined square enclosure was numerically investigated. The left ... more Natural convection of air in an inclined square enclosure was numerically investigated. The left and right walls of the enclosure were maintained at the uniform hot and cold temperatures, respectively, while the top and bottom walls were adiabatic. The enclosure was filled with real air, a compressible Newtonian fluid. The finite volume method was employed to discretize the partial differential equations of airflow in the enclosure. The angles of the inclination of a square enclosure giving the maximum average Nusselt numbers are   110 o for Ra = 110 3 and   130 o for 310 3  Ra 110 4 .

International Journal of Thermal Sciences, Feb 1, 2022

Abstract Direct numerical simulation (DNS) is a powerful research technique to solve the Navier–S... more Abstract Direct numerical simulation (DNS) is a powerful research technique to solve the Navier–Stokes equations based on turbulent flows. DNS delivers highly reliable physical solutions with extreme accuracy. Unfortunately, present hardware and computing technologies remain limited, making it difficult to implement DNS in practice. The recently proposed Lagrange interpolating polynomial (LIP) scheme is a discretization technique for the finite-volume method. The LIP scheme is easy to use with nonuniform grid simulations and can flexibly increase or decrease the order of accuracy. The objective of this study is to verify that the LIP scheme is suitable for DNS of natural convection in a square cavity at high Rayleigh numbers (Ra). Accordingly, code was developed in-house using a second-order LIP scheme with the finite-volume method and the semi-implicit method for pressure-linked equations (SIMPLE) algorithm. Simulations were performed at Ra values of 109 and 1.58 × 109. The solutions were then verified against experimental benchmark data and published numerical solutions. The maximum differences in the Nusselt numbers between the computed solutions and the experimental benchmark data and published numerical solutions are 19.23% and 5.51%, respectively. However, the comparison results indicate that most of the computed solutions are in good agreement with experimental benchmark data and published numerical solutions.

IOP Conference Series: Materials Science and Engineering, 2021

Solution differences of natural convection in a tall cavity filled with air in which the density ... more Solution differences of natural convection in a tall cavity filled with air in which the density of the body force term are approximated by using the Boussinesq approximation (BA) and by using the real air density equation (RE) are numerically investigated. The main parameters for the investigation are Nusselt numbers and numbers of cells in the multi-cellular flow. The investigation is carried out for the Rayleigh number of 104, and the cavity aspect ratio equal to 60. The temperature differences of the vertical cavity walls are varied from 1 K to 200 K. These conditions are appropriate to form the multi-cellular flow in the tall cavity obviously, and close to the boundary of the laminar and turbulent flows. Consequently, the differences in both Nusselt numbers and numbers of the cells in the multi-cellular flow can be easily observed. The finite volume method with the Lagrange interpolating polynomial (LIP) scheme are selected to discretize the governing equations of the flow, and...

MATEC Web of Conferences, 2017

Modification of the Lagrange interpolating polynomial (LIP) scheme for using with the finite diff... more Modification of the Lagrange interpolating polynomial (LIP) scheme for using with the finite difference method is proposed. Merits of the modified LIP scheme used with the finite difference method for problem solving are facile to discretize equations, and fast to obtain solutions. Verification of the modified LIP scheme was performed by comparison of the solutions computed from the modified LIP scheme with the analytical solutions of a heat conduction problem. The verification gives credence to the modified LIP scheme for correctness of the solutions. In addition, the comparison results of solution accuracy and computational time of problem solving between using of the finite difference method with the modified LIP scheme and the finite volume method with the LIP scheme are exhibited. Recently, the Lagrange interpolating polynomial (LIP) scheme for using with the FVM was proposed by Prasopchingchana and Manewattana [7]. The LIP scheme is easily modified for using with the FDM, called the modified LIP scheme. An aim of this article is to propose a modified LIP scheme for using with the FDM. The modified LIP scheme is a high-order scheme used for discretization of the first and second derivatives of variables with respect to both space and time. Using the modified LIP scheme with the FDM to solve problems simulated by using non-uniform grids is facile, and solution convergence of the using is fast.

International Journal of Thermal Sciences

Engineering Journal

A new scheme applied to the finite volume method for solving the partial differential equations o... more A new scheme applied to the finite volume method for solving the partial differential equations of fluid flow is proposed. The Lagrange interpolating polynomial with a setting of zero for the spatial domain at the cell faces, and the present time at the cell center is adopted for the new scheme to estimate the values of the variables at the cell faces, the derivative values of the variables with respect to the spatial domain at the cell faces and the derivative values of the variables with respect to time at the cell center for spatial and temporal discretization of the discretized equation. The new scheme was verified by comparing the solutions of the new scheme to the benchmark numerical solutions and the published numerical solutions of two dimensional laminar natural convection in a square cavity. From the comparison, the results show that the solutions of the new scheme agree well with the benchmark numerical solutions and the published numerical solutions.