Introduction

In ANSYS FLUENT the dynamic mesh capability is used to simulate problems with boundary motion, such as check valves and store separations. The building blocks for dynamic mesh capabilities within ANSYS FLUENT are three dynamic mesh schemes, namely, smoothing, layering, and remeshing. A combination of these three schemes are used to tackle the most challenging dynamic mesh problems. However, for simple dynamic mesh problems involving linear boundary motion, the layering scheme is often sufficient. For example, flow around a check valve can be simulated using only the layering scheme. In this tutorial, such a case will be used to demonstrate the layering feature of the dynamic mesh capability in ANSYS FLUENT.

Check valves are commonly used to allow uni-directional flow. For instance, they are often used to act as a pressure-relieving device by only allowing fluid to leave the domain when the pressure is higher than a certain level. In such a case, the check valve is connected to a spring that acts to push the valve to the valve seat and to shut the flow. But when the pressure force on the valve is greater than the spring force, the valve will move away from the valve seat and allow fluid to leave, thus reducing the pressure upstream. Gravity could be another factor in the force balance, and can be considered in ANSYS FLUENT. The deformation of the valve is typically neglected and thus allows for a rigid body Fluid Structure Interaction (FSI) calculation, for which a UDF is provided.

This tutorial provides information for performing basic dynamic mesh calculations. This tutorial demonstrates how to do the following:

• Use the dynamic mesh capability of ANSYS FLUENT to solve a simple flow-driven rigid-body motion problem.

• Set boundary conditions for internal flow.

• Use a compiled user-defined function (UDF) to specify flow-driven rigid-body motion.

• Calculate a solution using the pressure-based solver.

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Release 12.0 © ANSYS, Inc. 2009-02-09