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This example is taken from Cornell University’s ANSYS AIM Learning Modules

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Contents

1. Problem Specification
2. Geometry
3. Mesh
4. Physics Setup
5. Results
6. Validation

Problem Specification

The Ahmed Body is a standard wind tunnel model used to represent ground vehicles. It was first defined and characterized by S.R. Ahmed in 1984 and has been used since to study the effects of drag and aspect ratio. Below is the blueprint definition of an Ahmed body.

In this tutorial, we will subject an Ahmed body to air at 40 m/s in order to find the velocity vectors, pressures on the body, and streamlines around the body.

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Geometry

In this video, you will learn to import the geometry and create an Enclosure for analysis.

 

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Mesh

In this example, we will be using Automatic Physics-Aware Meshing. Automatic physics-aware meshing helps automate and simplify your problem setup. With automatic physics-aware meshing, the computational mesh is generated automatically based on the solution fidelity setting and the physics inputs.

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Physics Setup

This video shows how to set up boundary conditions to the fluid volume. One of the faces of the Fluid volume is given symmetry boundary condition and other faces apart from the Inlet and Outlet are given as Openings.

 

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Results

In this video, we will learn to generate results in the form of  Velocity Vector, Pressure contours and we will also generate Streamlines for the Ahmed Body.

 

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Validation

An excellent way of validating simulations is by comparing them to research papers which are relevant. Since the Ahmed body is so widely studied and used as validation, it is not difficult to find supporting evidence. For this tutorial, the information gathered from the simulation will be compared to “Embedded Large Eddy Simulation of Flow around the Ahmed Body” by Domenico Caridi done in ANSYS FLUENT. Below is a contour of the pressure on the rear surface of the Ahmed body. This can be compared to our model by creating a similar contour in our simulation.