Mark E. Gleason

Rapid simulation methodology for under-hood aero/thermal management

Computational Fluid Dynamics (CFD) has witnessed significant advances in the last half decade making it applicable to a wide range of problems in the automotive industry. The advent of unstructured grid technology, improved physical modelling capabilities such as phase change, radiation etc., have contributed to the increased use of CFD in automotive applications. In spite of the use of unstructured grids, the area of under-hood airflow and thermal simulation still requires significant amounts of time for grid generation. The paper describes a new approach which uses a Cartesian based grid system that allows for generating completed under-hood meshes within 2-3 days. In addition, discussion about using a local (body fitted grid) model to address thermal issues is presented. This represents an optimal combination of tools to obtain useful information for making engineering design decisions.

Numerical investigation of the effects of base slant on the wake pattern and drag of three-dimensional bluff bodies with a rear blunt end

Abstract A computational model has been developed to help the automotive design engineer to optimize the body shape with minimum wind tunnel testing. Unsteady, Reynolds-averaged, Navier-Stokes equations have been solved numerically by a finite-volume method and have been applied to study the flow around Ahmeds vehicle-like body. The standard k—e model has been employed to model the turbulence in the flow. The finite volume equations have been formulated in a strong conservative form on a three-dimensional, unstructured grid system. The resulting equations have been solved then by an implicit, time marching pressure-correction based algorithm. The steady state solution has been obtained by taking sufficient time steps until the flow field ceases to change with time within a prescribed tolerance. For the pressure-correction equation, a preconditioned conjugate gradient method has been employed to obtain the solution. Most of the essential features of the flow field around a bluff body in ground proximity, such as the formation of trailing vortices and the reverse flow region resulting from separation, could be well predicted. In addition, the variation of the drag coefficient with the back slant angle agreed reasonably well with the experimentally observed values.

Flow structure around a 3D bluff body in ground proximity: A computational study

Abstract A computational model is developed to help the automotive design engineer to optimize the body shape with minimum wind tunnel testing. Unsteady, Reynolds-averaged, Navier-Stokes equations are solved numerically by a finite-volume method and applied to study the flow around GMs vehicle-like body. The standard k-ϵ model is employed to model the turbulence in the flow. The finite volume equations are formulated in a strong conservative form on a three-dimensional, unstructured grid system. The resulting equations are then solved by an implicit, time marching, pressure-correction based algorithm. The steady state solution is obtained by taking sufficient time steps until the flow field ceases to change with time within a prescribed tolerance. For the pressure-correction equation, preconditioned conjugate gradient method is employed to obtain the solution. Most of the essential features of the flow field around a bluff body in ground proximity, such as the formation of trailing vortices and the reverse flow region resulting from separation, were well predicted. In addition, the variation of drag coefficient with Reynolds number per meter faithfully follows the experimentally observed pattern.

A critical study on the influence of far field boundary conditions on the pressure distribution around a bluff body

Abstract A computational model is developed to help the automotive design engineer to optimize the body shape with minimum wind tunnel testing. Unsteady, Reynolds-averaged, Navier-Stokes equations are solved numerically by a finite-volume method and applied to study the flow around a 3 8 th scale model of 1994 Intrepid. The standard k − e model is employed to model the turbulence in the flow. The finite volume equations are formulated in a strong conservative form on a three-dimensional, unstructured grid system. The resulting equations are then solved by an implicit, time marching, pressure-correction based algorithm. The steady state solution is obtained by taking sufficient time steps until the flow field ceases to change with time within a prescribed tolerance. For the pressure-correction equation, preconditioned conjugate gradient method is employed to obtain the solution. Numerical predictions were obtained with two different boundary conditions at the far field: (a) no flow across this boundary (b) the gradient of any variable normal to this boundary was set to zero. Drag predictions obtained with boundary condition (b) was in good agreement with the available experimental data.