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Current state-of-the-art in automotive computational aerodynamics relies on either multi-block structured grids or homogeneous unstructured tetra or hexa meshes. This paper presents a novel approach of unstructured solution-adaptive grids and a generalized tree-based Adaptive Cartesian/Prismatic (ACP) grid concept for automotive aerodynamic applications. The proposed concept resolves several problems which plague tetrahedral grids such as boundary layer grid cell aspect ratio or large grid count. ACP employs unstructured adaptive layer of prisms (or quads in 2D) near solid walls intersected with an adaptive tree-based Cartesian mesh in the rest of the computational space. The prismatic layer resolves the viscous wall layer with high aspect ratio mesh whereas the Cartesian tree mesh provides the smooth grid transition, allows grid coarsening and offers the best support for accurate numerical schemes.

This study is a joint development project between Chrysler Corporation and CFD Research Corporation. The objective of this investigation was to develop a 3D computational flow and heat transfer model for a vehicle windshield de-icing process. The windshield clearing process is a 3D transient, multi-medium, multi-phase heat exchange phenomenon in connection with the air flow distribution in the passenger compartment. The transient windshield de-icing analysis employed conjugate heat transfer methodology and enthalpy method to simulate the velocity distribution near the windshield inside surface, and the time progression of ice-melting pattern on the windshield outside surface. The comparison between the computed results and measured data showed very reasonable agreement, which demonstrated that the developed analysis tool is capable of simulating the vehicle cold room de-icing tests.

A numerical study of an automotive windshield ice-clearing was successfully accomplished. The windshield clearing process is a 3D transient, multi-medium, multi-phase heat exchange phenomenon in connection with the air flow distribution in the passenger compartment. The transient windshield clearing analysis employed conjugate heat transfer and enthalpy methods to simulate the ice-melting pattern and the melting duration. This study is a joint project between Chrysler Corporation and CFD Research Corporation. A Chrysler prototype windshield and test vehicle were utilized. The meshing was done using ICEM/CFD package by Control Data Corporation (CDC). A seamless data transfer was achieved by developing an interface between ICEM/CFD and CFD-ACE. The analysis of air flow, conjugate heat transfer, and weather clearing was performed using the multi-domain CFD-ACE code developed by CFD Research Corporation (CFDRC).

An advanced multi-domain CFD analysis approach is proposed to calculate the scavenging flow process in motored two-stroke engines. An implicit and conservative treatment at the domain interface is developed which offers significant speedup in convergence. An arbitrary Lagrangian-Eulerian approach for moving grid and a grid remeshing technique for grid sliding at engine cylinder/transfer ports interfaces are used for efficiency and accuracy. A three-dimensional simulation of the Mercury Marine research two-stroke engine is carried out to demonstrate the approach. Six computational domains are used which naturally represent the geometries of the cylinder, engine dome, exhaust and transfer ports. The influence of boost port inclination angle on the scavenging process of the two-stroke engine is also studied numerically. The computation is supplemented with a standard two-equation turbulence model with compressibility correction.

The paper presents three-dimensional simulations of the in-cylinder processes in Direct Injection (DI) Diesel Engines. First, mathematical formulation is described with emphasis on physical models used for turbulence, interphase friction, evaporation and chemical reaction. Then, the results of 3D transient calculations of the two-phase fuel-air mixing and evaporation processes are presented. Four test cases have been considered to demonstrate the effects of changes in: a) fuel injector, b) computational grid, and c) initial air swirl velocity. Computed results show that each of these parameters has significant effect on the spread and evaporation of liquid fuel spray. The results of low and high air swirl cases are in qualitative agreement with published experimental observations. Finally, a test calculation of 3D, two-phase flow with evaporation and combustion is presented for demonstration purposes.