Help needed with moving model in CFX
 

I am a student at the University of Bath and am currently partaking in a final year project which is looking into simulating the flow within a single cylinder internal combustion engine. I am a new user to CFD software so I do not have much experience of the tools and methods used for simulations.

I have started by modelling a simple cross section of a cylinder and inlet valve and have been able to incorporate the methods (with modifications to the expressions) used in the Ansys tutorial, Fluid Structure Interaction and Mesh Deformation, to move the simple piston downwards in the cylinder.

The problem I am having is to produce an accurate model for the engine I want to simulate I would like to be able to enter data for the pressures, mass flow rate at inlet and displacement of the piston into a model in Ansys. I have not found anyway of doing this and wondered if there was such a way? I have tried entering data for the displacement of the piston as a User Function but I can't find a way of using this function to relate it to the mesh displacement and the movement of the piston.

I appreciate this is a very broad question, and any help you could give me would be very much appreciated.

Steve

Hi Steve,

if i understand right, you have problems with implementing a user function which later is used for mesh motion ? If i´m right you should do the following:

-create user function:
e.g. "DataX" displacement over time (Argument = t, Result = displacement or postion) you can also import spread sheet data.
-create expression:
e.g. DispXWallTop = DataX(t)
-now you can use the expression DispXWallTop to define a specific mesh mesh motion

p.s. same procedure for any other data you want to import as spread sheet
regards

MAtthias