You have to use the solid mesh and give the velocity of the wall motion by using the function  UDF (User Defined Functions) for the dynamic mesh.

You can write UDF (User Defined Functions) for dynamic mesh motion.

you used use just one solid mesh for your simulation. then give a a specified motion to walls using your function (whatever you define) and apply it on the computation using Dynamic mesh. in Fluent you should write UDF and link the walls to obbey this UDF.

hope it would be useful

You have to use the solid mesh and give the velocity of the wall motion by using the function  UDF (User Defined Functions) for the dynamic mesh.

example

It seems good. The choice of the update method is very important; it depends on the geometry and the variation of your boundary conditions.... 

thank you all for answering

it seems that the best thing to do is using a udf

now i have coordinates of nodes for each time step and want to write a udf that reads this data from an external file, but i'm stuck with it! if you could help me i would be very grateful

Hi there,

Maybe a step further ahead, do you have a function which defines mesh nodes coordinates or their velocity? If so, you can use Define_Grid_Motion macro. Other than that, you may face some difficulties assigning the correct location to mesh nodes. However, there may be some workarounds, for instance specifying different zone ID to a set of nodes close to each others, in order to move these zones separately inside the grid_motion UDF. Or you could use Ansys Optimization to prescribe some predefined coordinates to several control point (CP) around your geometry. Though wrt the latter I am not sure whether you can use a previous solution as the initial condition for the new one, but worth a try!

As the last resort, you should be able to find out the order on which the mesh nodes are arranged and called within a loop inside the Grid_Motion macro.

Regards

Dear ehsan

 I am grateful for your response. I don't have a function, just coordinates for each node each time step. actually i wrote a udf to change the position of nodes. i can read data, apply it and repeat this for next time step, the problem is because of  large number of time steps i can't apply every one of them.

Hi Faeze, I am facing the same question and want to simulate the heart wall motion. Could you help me?

Thank you so much!