Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, 2005
This paper presents a simulation study into the characteristics of a vehicle experiencing steerin... more This paper presents a simulation study into the characteristics of a vehicle experiencing steering drift under straight line braking. Simulation modelling has been performed using a multi-body dynamics analysis based on a model of an actual vehicle. Front and rear suspension parameters have been modelled as rigid links joined with flexible bushes so as to assess their effect on a vehicle while braking. Suspension geometry and alignment settings, which define characteristic responses such as lateral acceleration, yaw velocity, toe, and caster angles of a vehicle in a transient manoeuvre, are primary to a vehicle's directional stability. Any symmetric inconsistencies in these settings will potentially affect a vehicle's performance. The findings from this research have increased the understanding of the causes of steering drift during braking conditions.
The conjugate natural convection heat transfer in a partially heated square porous enclosure had ... more The conjugate natural convection heat transfer in a partially heated square porous enclosure had been studied numerically. The governing dimensionless equations are solved using COMSOL Multiphysics and Darcy model assumed to be used. The considering dimensionless parameters are modified Rayleigh number, finite wall thickness, thermal conductivity ratio and the heat source length. The results are presented in terms of streamlines, isotherms and local and average Nusselt number. The results indicate that; the heat transfer can be enhanced by increasing the modified Rayleigh number. When the heat source length increases, the local Nusselt number of fluid phase increases, while, a reverse behavior of the local Nusselt number along the heat source is found. As the Rayleigh number increase, the local Nusselt number for both fluid and solid phase increases, therefore, the heat transfer rate will be enhanced. On the other hand, when the thermal conductivity ratio increase, the local Nusselt number for the fluid phase increases, and the local Nusselt number along the heated wall decreases.
Based on the common approach, the adaptation length in sediment transport is normally estimated i... more Based on the common approach, the adaptation length in sediment transport is normally estimated in the temporal independence. However, this approach might not be theoretically justified as the process of reaching of the sediment transport equilibrium stage is affected by the flow conditions in time, especially for those fast sediment moving flows, such as scour-hole developing flow. In this study, the 2D shallow water formulation together with a sediment continuity-concentration (SCC) model were applied to flow with mobile sediment boundary. A time-varying approach was proposed to determine the sediment transport adaptation length to treat the flow sediment erosion-deposition rate. The proposed computational model was based on the Finite Volume (FV) method. The Monotone Upwind Scheme of Conservative Laws (MUSCL)-Hancock scheme was used with the Harten Lax van Leer-contact (HLLC) approximate Riemann solver to discretize the FV model. In the flow applications of this paper, a highly discontinuous dam-break fast sediment transport flow was used to calibrate the proposed time-varying sediment adaptation length model. Then the calibrated model was further applied to two separate experimental sediment transport flow applications documented in literature, i.e. a highly concentrated sediment transport flow in a wide alluvial channel and a sediment aggradation flow. Good agreements with the experimental data were presented by the proposed model simulations. The tests prove that the proposed model, which was calibrated by the discontinuous dam-break bed scouring flow, also performed well to represent the rapid bed change and the steady sediment mobility conditions.
The coupling between natural convection and conduction within rectangular enclosure was investiga... more The coupling between natural convection and conduction within rectangular enclosure was investigated numerically. Three separate heat sources were flush mounted on a vertical wall and an isoflux condition was applied at the back of heat sources. The governing equations were solved using control volume formulation. A modified Rayleigh number and a substrate/fluid thermal conductivity ratio were used in the range \( {10}^4-{10}^7 \) and \( 10-{10}^3 \) respectively. The investigation was extended to examine high thermal conductivity ratio values. The results illustrated that, when Rayleigh number increased the dimensionless heat flux and local Nusselt number increased and the boundary layers along hot, cold and horizontal walls were reduced significantly. An opposite behaviour for the thermal spreading in the substrate and the dimensionless temperature, were decreased for higher Rayleigh number. Moreover, the thermal spreading in the substrate increased for higher substrate conductivity, which affected the temperature level. However the effect of the substrate is negligible when the thermal conductivity ratio higher than 1,500.
Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, 2005
This paper presents a simulation study into the characteristics of a vehicle experiencing steerin... more This paper presents a simulation study into the characteristics of a vehicle experiencing steering drift under straight line braking. Simulation modelling has been performed using a multi-body dynamics analysis based on a model of an actual vehicle. Front and rear suspension parameters have been modelled as rigid links joined with flexible bushes so as to assess their effect on a vehicle while braking. Suspension geometry and alignment settings, which define characteristic responses such as lateral acceleration, yaw velocity, toe, and caster angles of a vehicle in a transient manoeuvre, are primary to a vehicle's directional stability. Any symmetric inconsistencies in these settings will potentially affect a vehicle's performance. The findings from this research have increased the understanding of the causes of steering drift during braking conditions.
The conjugate natural convection heat transfer in a partially heated square porous enclosure had ... more The conjugate natural convection heat transfer in a partially heated square porous enclosure had been studied numerically. The governing dimensionless equations are solved using COMSOL Multiphysics and Darcy model assumed to be used. The considering dimensionless parameters are modified Rayleigh number, finite wall thickness, thermal conductivity ratio and the heat source length. The results are presented in terms of streamlines, isotherms and local and average Nusselt number. The results indicate that; the heat transfer can be enhanced by increasing the modified Rayleigh number. When the heat source length increases, the local Nusselt number of fluid phase increases, while, a reverse behavior of the local Nusselt number along the heat source is found. As the Rayleigh number increase, the local Nusselt number for both fluid and solid phase increases, therefore, the heat transfer rate will be enhanced. On the other hand, when the thermal conductivity ratio increase, the local Nusselt number for the fluid phase increases, and the local Nusselt number along the heated wall decreases.
Based on the common approach, the adaptation length in sediment transport is normally estimated i... more Based on the common approach, the adaptation length in sediment transport is normally estimated in the temporal independence. However, this approach might not be theoretically justified as the process of reaching of the sediment transport equilibrium stage is affected by the flow conditions in time, especially for those fast sediment moving flows, such as scour-hole developing flow. In this study, the 2D shallow water formulation together with a sediment continuity-concentration (SCC) model were applied to flow with mobile sediment boundary. A time-varying approach was proposed to determine the sediment transport adaptation length to treat the flow sediment erosion-deposition rate. The proposed computational model was based on the Finite Volume (FV) method. The Monotone Upwind Scheme of Conservative Laws (MUSCL)-Hancock scheme was used with the Harten Lax van Leer-contact (HLLC) approximate Riemann solver to discretize the FV model. In the flow applications of this paper, a highly discontinuous dam-break fast sediment transport flow was used to calibrate the proposed time-varying sediment adaptation length model. Then the calibrated model was further applied to two separate experimental sediment transport flow applications documented in literature, i.e. a highly concentrated sediment transport flow in a wide alluvial channel and a sediment aggradation flow. Good agreements with the experimental data were presented by the proposed model simulations. The tests prove that the proposed model, which was calibrated by the discontinuous dam-break bed scouring flow, also performed well to represent the rapid bed change and the steady sediment mobility conditions.
The coupling between natural convection and conduction within rectangular enclosure was investiga... more The coupling between natural convection and conduction within rectangular enclosure was investigated numerically. Three separate heat sources were flush mounted on a vertical wall and an isoflux condition was applied at the back of heat sources. The governing equations were solved using control volume formulation. A modified Rayleigh number and a substrate/fluid thermal conductivity ratio were used in the range \( {10}^4-{10}^7 \) and \( 10-{10}^3 \) respectively. The investigation was extended to examine high thermal conductivity ratio values. The results illustrated that, when Rayleigh number increased the dimensionless heat flux and local Nusselt number increased and the boundary layers along hot, cold and horizontal walls were reduced significantly. An opposite behaviour for the thermal spreading in the substrate and the dimensionless temperature, were decreased for higher Rayleigh number. Moreover, the thermal spreading in the substrate increased for higher substrate conductivity, which affected the temperature level. However the effect of the substrate is negligible when the thermal conductivity ratio higher than 1,500.
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Papers by Khalid Hussain