Can anybody help me to write down a CEL to define a piston motion with moving grid?

How about A/2*(1+sin(omega*t)) Assuming your piston starts at the bottom position and A is equal to the sweep distance. Omega should be the frequency in radians per second (i.e. omeaga=2*pi*f, where f is the frequency).

The mesh distortion will be less if you start the piston in the middle position, in which case you should use A/2*sin(omega*t).

Regards, Robin

Hi,

Actually Robin, for piston motion mesh deformation with the current model available in CFX5 you have to start the piston at top dead centre. You then define the piston motion relative to the TDC position.

If you start anywhere else, when you get to TDC later in the stroke you often get elements turning inside out.

Regards, Glenn Horrocks

[mohammedammeen]

Originally Posted by Glenn Horrocks
;73382

Hi,

Actually Robin, for piston motion mesh deformation with the current model available in CFX5 you have to start the piston at top dead centre. You then define the piston motion relative to the TDC position.

If you start anywhere else, when you get to TDC later in the stroke you often get elements turning inside out.

Regards, Glenn Horrocks

please help me in do the motion meshing in a hydrolic cylinder with grade 45 oil

[ghorrocks]

Your question is just about exactly the example of how not to ask a question on the forum in the FAQ: http://www.cfd-online.com/Wiki/Ansys...ible_answer.3F