# moving mesh

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 April 10, 2005, 23:33 moving mesh #1 sulfi Guest   Posts: n/a Dear friends, could you tell me how to do the moving mesh analysis in fluent. my case is a planing craft, which should move up and down due to the dynamic pressure acting on it. Please send me any moving mesh tutorial which will help me doing the same. thanking u sulfi

 April 11, 2005, 02:56 Re: moving mesh #2 handou Guest   Posts: n/a you should use the dynamic mesh method. write a udf to describe your motion. do you have the FLUENT tutorial files? there is a example very similar to yours.

 April 11, 2005, 13:42 Re: moving mesh #3 sulfi Guest   Posts: n/a handou thank u for ur reply in fluents sliding mesh tutorials they are specifying the rotor motion velocity as the velocity of the mesh. But i am simulating a planing craft which should move depending on the dynamic pressure acting on its bottom. please help me doing the above problem. send me if u have any other turorials of moving mesh thanking u

 April 12, 2005, 08:36 Re: moving mesh #4 handou Guest   Posts: n/a this is a example in the guide. hope it can help. #include "udf.h" static real v_prev = 0.0; DEFINE_CG_MOTION(piston, dt, vel, omega, time, dtime) { Thread *t; face_t f; real NV_VEC (A); real force, dv; /* reset velocities */ NV_S (vel, =, 0.0); NV_S (omega, =, 0.0); if (!Data_Valid_P ()) return; /* get the thread pointer for which this motion is defined */ t = DT_THREAD (dt); /* compute pressure force on body by looping through all faces */ force = 0.0; begin_f_loop (f, t) { F_AREA (A, f, t); force += F_P (f, t) * NV_MAG (A); } end_f_loop (f, t) /* compute change in velocity, i.e., dv = F * dt / mass velocity update using explicit Euler formula */ dv = dtime * force / 50.0; v_prev += dv; Message ("time = %f, x_vel = %f, force = %f\n", time, v_prev, force); /* set x-component of velocity */ vel[0] = v_prev; }

 April 12, 2005, 08:54 Re: moving mesh #5 sulfi Guest   Posts: n/a thank u handou. But i am not able to follow the uDF properly. can u send the whole example of the guide.so that i can solve that problem which may help me better understand how to set up a moving mesh problem and may help me to write the UDF. can u explain the UDF eloberately

 April 12, 2005, 09:32 Re: moving mesh #6 handou Guest   Posts: n/a sorry, i never used this udf before. i just copy it from the help file for you. don't you have the udf help file? it's about 2MB big. can i send it to your email?

 April 12, 2005, 16:58 Re: moving mesh #7 Shuto Guest   Posts: n/a I think this problem is quite difficult especially if you have no former experience with a dynamic mesh. If the flow is going to drive the motion of the body you will need to incorporate feedback from the simulation into the udf. I recommend that initially you write a very simple udf to produce linear motion. Once you have got that working then move on to incorporating flow effects. Hope this helps, Shuto.

 April 13, 2005, 23:52 Re: moving mesh #8 sulfi Guest   Posts: n/a Dear handou, i havnt got the two files sent by you. file. when i downloaded the message came file corrupted. can u send it again. Thanking u sulfi