Tutorial: 2D Adiabatic Compression - Layering

Introduction

This tutorial illustrates the setup and solution of a basic deforming mesh in FLUENT using the layering approach.

The dynamic mesh model in FLUENT can be used to model flows where the shape of the domain is changing with time due to motion on the domain boundaries. The motion can be either a prescribed motion (e.g., you can specify the linear and angular velocities about the center of gravity of a solid body with time) or an unsubscribed motion where the subsequent motion is determined through a user-defined function (UDF). The update of the volume mesh is handled automatically by FLUENT at each time step based on the new positions of the boundaries. To use the dynamic mesh model, you need to provide a starting volume mesh and the description of the motion of any moving zones in the model.

In this tutorial, you will use the layering mesh motion method to update the volume mesh in the deforming region. You will setup and solve the case for both types of layering; Bottom Layering and Top Layering. Layering can be used to add or remove layers of cells adjacent to a moving boundary based on the height of the layer adjacent to the moving surface. The first part will involve Bottom Layering, and the second part the Top Layering. The dynamic mesh model in FLUENT allows an ideal layer height to be specified on each moving boundary. The layer of cells adjacent to the moving boundary is subdivided or merged with the layer of cells next to it based on the height of the cells in the moving boundary

Problem Description
The problem to be considered is shown schematically in Figure 1. A simplified 2D geometry is used, consisting of a box, the bottom wall of which represents the piston. The piston moves up from bottom dead center position (BDC), slowly compressing the fluid adiabatically. After reaching top dead center (TDC), the piston moves back downward to the initial position, to complete a cycle