M. A. Omar Awang - Academia.edu (original) (raw)

Uploads

Papers by M. A. Omar Awang

Research paper thumbnail of Unsteady free convection from a heated sphere at high grashof number

Journal of Engineering Mathematics, Dec 1, 1983

The free-convective boundary-layer flow over the surface of a sphere whose temperature is suddenl... more The free-convective boundary-layer flow over the surface of a sphere whose temperature is suddenly raised to a value greater than its surroundings is considered. Numerical solutions of the boundary-layer equations are presented which give a complete description of the flow and which confirm the appearance of a singularity in the solution at the upper pole after a finite time.

Research paper thumbnail of Heat Transfer Enhancement in a Microchannel Heat Sink with Trapezoidal Cavities on the Side Walls

Applied Mechanics and Materials, 2016

An improved design of wavy microchannel heat sink with changing wavelength or/and amplitude along... more An improved design of wavy microchannel heat sink with changing wavelength or/and amplitude along the flow direction is proposed. The thermal resistance R and the maximum bottom wall temperature difference DT b,max for the new design are compared with those for the straight and the original wavy design under a constant pumping power. The results show that the new design performance is enhanced significantly with lower R and smaller DT b,max when the wavelength of wavy units decreases or the amplitude increases. The enhancement becomes more remarkably when the absolute value of the wavelength difference Dl or amplitude difference DA between two adjacent wavy units increases. The performance can be further improved by simultaneously increasing the absolute values of Dl and DA. Moreover, as compared with the straight and the original wavy microchannel heat sink, the reductions in R and DT b,max for the new design is found more significant for the heat sink with a smaller channel aspect ratio. The heat transfer enhancement is attributed to the formation of vortices in the channel cross sections caused by the curved walls, which promotes the coolant mixing and enhances the convective heat transfer between coolant and channel walls.

Research paper thumbnail of Response time analysis for suspended sediment transport

Journal of Hydraulic Research, May 1, 1998

Page 1. Response time analysis for suspended sediment transport Annalyse temporelle du transport ... more Page 1. Response time analysis for suspended sediment transport Annalyse temporelle du transport de sediments en suspension PETER K. STANSBY AND MAOMAR AWANG, Hydrodynamics Research Group, Manchester ...

Research paper thumbnail of The role of vaccination in curbing tuberculosis epidemic

Modeling Earth Systems and Environment, Sep 13, 2019

This work studies the impact of vaccine in controlling tuberculosis (TB) epidemic using susceptib... more This work studies the impact of vaccine in controlling tuberculosis (TB) epidemic using susceptible, vaccinated, exposed, infectious and recovered compartmental model. This is necessitated due to the acclaimed ineffectiveness of BCG vaccine in combatting TB. The model is formulated using a non-linear system of ordinary differential equation which is normalised to eliminate the natural death factor () so as to focus on other factors. The disease-free equilibrium and endemic equilibrium point (EEP) of the system are established alongside their local and global stabilities. Although the local stability of the EEP could not be established analytically due to the cumbersomeness of the EEP obtained, it is, however, established numerically. It is shown with the aid of numerical simulation carried out on the model that vaccination helps in reducing the tuberculosis epidemic and in fact, if the rates of contact and infectivity are reduced, further reduction in the rate of incidence () can be achieved. Further more, the reason why there is the need for a better vaccine to replace BCG vis-á-vis provision of better immunity coverage (→ 0 and → 0) and also, the need for the development of drugs that confer permanent or long lasting immunity (2 → 0) is as well established. More vaccination proportion gives better outcome (→ 1) and the introduced controls show their relevance in reducing the infection. The novelty of this research is the provision of guiding frame work for the pharmacists on the intrinsic features expected of any proposed vaccine to replace BCG while the expected recommendations from the doctors are established using optimal control.

Research paper thumbnail of Improved calculations for the steady flow over a heated sphere at high Grashof number

Research paper thumbnail of Numerical simulation of metal removal in laser drilling using symmetric smoothed particle hydrodynamics

Precision Engineering, 2017

A simple numerical model is proposed for predicting the penetration depth of metal laser drilling... more A simple numerical model is proposed for predicting the penetration depth of metal laser drilling. A simplified 2D axisymmetric model for transient metal laser drilling is introduced. Strong-form of symmetric smoothed particle hydrodynamics (SSPH) method is used to harness its significant reduction in computational time. The 2D axisymmetric domain is discretized, then SSPH formulation is used to obtain shape functions. Collocation method is used to discretize governing and boundary conditions equations to construct the global stiffness matrix. Laser beam is assumed to be continuous wave with Gaussian distribution. MATLAB code is constructed for numerical simulation, and the results are compared with published work. A good agreement is shown, and thus the proposed numerical model is found to be computation

Research paper thumbnail of Response time analysis for suspended sediment transport

Journal of Hydraulic Research, 1998

Page 1. Response time analysis for suspended sediment transport Annalyse temporelle du transport ... more Page 1. Response time analysis for suspended sediment transport Annalyse temporelle du transport de sediments en suspension PETER K. STANSBY AND MAOMAR AWANG, Hydrodynamics Research Group, Manchester ...

Research paper thumbnail of Unsteady free convection from a heated sphere at high grashof number

Journal of Engineering Mathematics, 1983

The free-convective boundary-layer flow over the surface of a sphere whose temperature is suddenl... more The free-convective boundary-layer flow over the surface of a sphere whose temperature is suddenly raised to a value greater than its surroundings is considered. Numerical solutions of the boundary-layer equations are presented which give a complete description of the flow and which confirm the appearance of a singularity in the solution at the upper pole after a finite time.

Research paper thumbnail of Stagnation-Point Flow toward a Vertical, Nonlinearly Stretching Sheet with Prescribed Surface Heat Flux

Journal of Applied Mathematics, 2013

An analysis is carried out to study the steady two-dimensional stagnation-point flow of an incomp... more An analysis is carried out to study the steady two-dimensional stagnation-point flow of an incompressible viscous fluid towards a stretching vertical sheet. It is assumed that the sheet is stretched nonlinearly, with prescribed surface heat flux. This problem is governed by three parameters: buoyancy, velocity exponent, and velocity ratio. Both assisting and opposing buoyant flows are considered. The governing partial differential equations are transformed into a system of ordinary differential equations and solved numerically by finite difference Keller-box method. The flow and heat transfer characteristics for different values of the governing parameters are analyzed and discussed. Dual solutions are found in the opposing buoyant flows, while the solution is unique for the assisting buoyant flows.

Research paper thumbnail of Boundary Layer Flow and Heat Transfer over an Exponentially Shrinking Sheet

Chinese Physics Letters, 2011

An analysis is made to study boundary layer flow and heat transfer over an exponentially shrinkin... more An analysis is made to study boundary layer flow and heat transfer over an exponentially shrinking sheet. Using similarity transformations in exponential form, the governing boundary layer equations are transformed into self-similar nonlinear ordinary differential equations, which are then solved numerically using a very efficient shooting method. The analysis reveals the conditions for the existence of steady boundary layer flow due to exponential shrinking of the sheet and it is found that when the mass suction parameter exceeds a certain critical value, steady flow is possible. The dual solutions for velocity and temperature distributions are obtained. With increasing values of the mass suction parameter, the skin friction coefficient increases for the first solution and decreases for the second solution.

Research paper thumbnail of Improved calculations for the steady flow over a heated sphere at high Grashof number

Research paper thumbnail of The analytical interface coupling of arbitrary-order fractional nonlinear hyperbolic scalar conservation laws

Advances in Difference Equations

In this paper, the existence and uniqueness of the interface coupling (IC) of time and spatial (T... more In this paper, the existence and uniqueness of the interface coupling (IC) of time and spatial (TS) arbitrary-order fractional (AOF) nonlinear hyperbolic scalar conservation laws (NHSCL) are investigated. The technique of arbitrary fractional characteristic method (AFCM) is used to accomplish this task. We apply Jumarie’s modification of Riemann–Liouville and Liouville–Caputo’s definition to extend some formulae to the arbitrary-order fractional calculus. Then these formulae are utilized to prove the main theorem. In this process, we develop an analytic method, which gives us the ability to find the solution of IC AOF NHSCL. The feature of this method is that it enables us to verify that the obtained solution satisfies the fractional partial differential equation (FPDE), and the solution is unique. Furthermore, a few examples illustrate the implementation of this technique in the application section.

Research paper thumbnail of The role of vaccination in curbing tuberculosis epidemic

Modeling Earth Systems and Environment

Research paper thumbnail of The arbitrary-order fractional hyperbolic nonlinear scalar conservation law

Advances in Difference Equations

In this paper, we use a new powerful technique of arbitrary-order fractional (AOF) characteristic... more In this paper, we use a new powerful technique of arbitrary-order fractional (AOF) characteristic method (CM) to solve the AOF hyperbolic nonlinear scalar conservation law (HNSCL) of time and space. We present the existence and uniqueness of this class of equations in time and one-dimensional space of fractional arbitrary order. We extend Jumarie’s modification of Riemann–Liouville and Caputo’s definition of the fractional arbitrary order to introduce some formulae (Appl. Math. Lett. 22:378–385, 2009; Appl. Math. Lett. 18:739–748, 2005). Then, we use these formulae to prove the main theorem. In the application section, we use the analytical technique that is presented in the theorem to solve examples that are given.

Research paper thumbnail of Unsteady free convection from a heated sphere at high grashof number

Journal of Engineering Mathematics, Dec 1, 1983

The free-convective boundary-layer flow over the surface of a sphere whose temperature is suddenl... more The free-convective boundary-layer flow over the surface of a sphere whose temperature is suddenly raised to a value greater than its surroundings is considered. Numerical solutions of the boundary-layer equations are presented which give a complete description of the flow and which confirm the appearance of a singularity in the solution at the upper pole after a finite time.

Research paper thumbnail of Heat Transfer Enhancement in a Microchannel Heat Sink with Trapezoidal Cavities on the Side Walls

Applied Mechanics and Materials, 2016

An improved design of wavy microchannel heat sink with changing wavelength or/and amplitude along... more An improved design of wavy microchannel heat sink with changing wavelength or/and amplitude along the flow direction is proposed. The thermal resistance R and the maximum bottom wall temperature difference DT b,max for the new design are compared with those for the straight and the original wavy design under a constant pumping power. The results show that the new design performance is enhanced significantly with lower R and smaller DT b,max when the wavelength of wavy units decreases or the amplitude increases. The enhancement becomes more remarkably when the absolute value of the wavelength difference Dl or amplitude difference DA between two adjacent wavy units increases. The performance can be further improved by simultaneously increasing the absolute values of Dl and DA. Moreover, as compared with the straight and the original wavy microchannel heat sink, the reductions in R and DT b,max for the new design is found more significant for the heat sink with a smaller channel aspect ratio. The heat transfer enhancement is attributed to the formation of vortices in the channel cross sections caused by the curved walls, which promotes the coolant mixing and enhances the convective heat transfer between coolant and channel walls.

Research paper thumbnail of Response time analysis for suspended sediment transport

Journal of Hydraulic Research, May 1, 1998

Page 1. Response time analysis for suspended sediment transport Annalyse temporelle du transport ... more Page 1. Response time analysis for suspended sediment transport Annalyse temporelle du transport de sediments en suspension PETER K. STANSBY AND MAOMAR AWANG, Hydrodynamics Research Group, Manchester ...

Research paper thumbnail of The role of vaccination in curbing tuberculosis epidemic

Modeling Earth Systems and Environment, Sep 13, 2019

This work studies the impact of vaccine in controlling tuberculosis (TB) epidemic using susceptib... more This work studies the impact of vaccine in controlling tuberculosis (TB) epidemic using susceptible, vaccinated, exposed, infectious and recovered compartmental model. This is necessitated due to the acclaimed ineffectiveness of BCG vaccine in combatting TB. The model is formulated using a non-linear system of ordinary differential equation which is normalised to eliminate the natural death factor () so as to focus on other factors. The disease-free equilibrium and endemic equilibrium point (EEP) of the system are established alongside their local and global stabilities. Although the local stability of the EEP could not be established analytically due to the cumbersomeness of the EEP obtained, it is, however, established numerically. It is shown with the aid of numerical simulation carried out on the model that vaccination helps in reducing the tuberculosis epidemic and in fact, if the rates of contact and infectivity are reduced, further reduction in the rate of incidence () can be achieved. Further more, the reason why there is the need for a better vaccine to replace BCG vis-á-vis provision of better immunity coverage (→ 0 and → 0) and also, the need for the development of drugs that confer permanent or long lasting immunity (2 → 0) is as well established. More vaccination proportion gives better outcome (→ 1) and the introduced controls show their relevance in reducing the infection. The novelty of this research is the provision of guiding frame work for the pharmacists on the intrinsic features expected of any proposed vaccine to replace BCG while the expected recommendations from the doctors are established using optimal control.

Research paper thumbnail of Improved calculations for the steady flow over a heated sphere at high Grashof number

Research paper thumbnail of Numerical simulation of metal removal in laser drilling using symmetric smoothed particle hydrodynamics

Precision Engineering, 2017

A simple numerical model is proposed for predicting the penetration depth of metal laser drilling... more A simple numerical model is proposed for predicting the penetration depth of metal laser drilling. A simplified 2D axisymmetric model for transient metal laser drilling is introduced. Strong-form of symmetric smoothed particle hydrodynamics (SSPH) method is used to harness its significant reduction in computational time. The 2D axisymmetric domain is discretized, then SSPH formulation is used to obtain shape functions. Collocation method is used to discretize governing and boundary conditions equations to construct the global stiffness matrix. Laser beam is assumed to be continuous wave with Gaussian distribution. MATLAB code is constructed for numerical simulation, and the results are compared with published work. A good agreement is shown, and thus the proposed numerical model is found to be computation

Research paper thumbnail of Response time analysis for suspended sediment transport

Journal of Hydraulic Research, 1998

Page 1. Response time analysis for suspended sediment transport Annalyse temporelle du transport ... more Page 1. Response time analysis for suspended sediment transport Annalyse temporelle du transport de sediments en suspension PETER K. STANSBY AND MAOMAR AWANG, Hydrodynamics Research Group, Manchester ...

Research paper thumbnail of Unsteady free convection from a heated sphere at high grashof number

Journal of Engineering Mathematics, 1983

The free-convective boundary-layer flow over the surface of a sphere whose temperature is suddenl... more The free-convective boundary-layer flow over the surface of a sphere whose temperature is suddenly raised to a value greater than its surroundings is considered. Numerical solutions of the boundary-layer equations are presented which give a complete description of the flow and which confirm the appearance of a singularity in the solution at the upper pole after a finite time.

Research paper thumbnail of Stagnation-Point Flow toward a Vertical, Nonlinearly Stretching Sheet with Prescribed Surface Heat Flux

Journal of Applied Mathematics, 2013

An analysis is carried out to study the steady two-dimensional stagnation-point flow of an incomp... more An analysis is carried out to study the steady two-dimensional stagnation-point flow of an incompressible viscous fluid towards a stretching vertical sheet. It is assumed that the sheet is stretched nonlinearly, with prescribed surface heat flux. This problem is governed by three parameters: buoyancy, velocity exponent, and velocity ratio. Both assisting and opposing buoyant flows are considered. The governing partial differential equations are transformed into a system of ordinary differential equations and solved numerically by finite difference Keller-box method. The flow and heat transfer characteristics for different values of the governing parameters are analyzed and discussed. Dual solutions are found in the opposing buoyant flows, while the solution is unique for the assisting buoyant flows.

Research paper thumbnail of Boundary Layer Flow and Heat Transfer over an Exponentially Shrinking Sheet

Chinese Physics Letters, 2011

An analysis is made to study boundary layer flow and heat transfer over an exponentially shrinkin... more An analysis is made to study boundary layer flow and heat transfer over an exponentially shrinking sheet. Using similarity transformations in exponential form, the governing boundary layer equations are transformed into self-similar nonlinear ordinary differential equations, which are then solved numerically using a very efficient shooting method. The analysis reveals the conditions for the existence of steady boundary layer flow due to exponential shrinking of the sheet and it is found that when the mass suction parameter exceeds a certain critical value, steady flow is possible. The dual solutions for velocity and temperature distributions are obtained. With increasing values of the mass suction parameter, the skin friction coefficient increases for the first solution and decreases for the second solution.

Research paper thumbnail of Improved calculations for the steady flow over a heated sphere at high Grashof number

Research paper thumbnail of The analytical interface coupling of arbitrary-order fractional nonlinear hyperbolic scalar conservation laws

Advances in Difference Equations

In this paper, the existence and uniqueness of the interface coupling (IC) of time and spatial (T... more In this paper, the existence and uniqueness of the interface coupling (IC) of time and spatial (TS) arbitrary-order fractional (AOF) nonlinear hyperbolic scalar conservation laws (NHSCL) are investigated. The technique of arbitrary fractional characteristic method (AFCM) is used to accomplish this task. We apply Jumarie’s modification of Riemann–Liouville and Liouville–Caputo’s definition to extend some formulae to the arbitrary-order fractional calculus. Then these formulae are utilized to prove the main theorem. In this process, we develop an analytic method, which gives us the ability to find the solution of IC AOF NHSCL. The feature of this method is that it enables us to verify that the obtained solution satisfies the fractional partial differential equation (FPDE), and the solution is unique. Furthermore, a few examples illustrate the implementation of this technique in the application section.

Research paper thumbnail of The role of vaccination in curbing tuberculosis epidemic

Modeling Earth Systems and Environment

Research paper thumbnail of The arbitrary-order fractional hyperbolic nonlinear scalar conservation law

Advances in Difference Equations

In this paper, we use a new powerful technique of arbitrary-order fractional (AOF) characteristic... more In this paper, we use a new powerful technique of arbitrary-order fractional (AOF) characteristic method (CM) to solve the AOF hyperbolic nonlinear scalar conservation law (HNSCL) of time and space. We present the existence and uniqueness of this class of equations in time and one-dimensional space of fractional arbitrary order. We extend Jumarie’s modification of Riemann–Liouville and Caputo’s definition of the fractional arbitrary order to introduce some formulae (Appl. Math. Lett. 22:378–385, 2009; Appl. Math. Lett. 18:739–748, 2005). Then, we use these formulae to prove the main theorem. In the application section, we use the analytical technique that is presented in the theorem to solve examples that are given.