CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > FLUENT

problem with oscillating cylinder

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Display Modes
Old   September 13, 2006, 10:44
Default problem with oscillating cylinder
  #1
zonexo
Guest
 
Posts: n/a
hi,

i'm trying to simulate a cylinder oscillating in a transverse fashion. i've met with some problems which i hope someone can help...

these are the steps i took:

1. read in the mesh

2. prepare the plung.c udf file given as

#include "udf.h" /* this function defines velocity of center of gravity for pure plunging motion*/ /* Plunging motion equation is z(t)=h*sin(2*pi*f*t) */ DEFINE_CG_MOTION(plung, dt, vel, omega, time, dtime) { Thread *t; face_t *f; /*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); */ /* vel[1] is the vertical plunging velocity */ /* These velocity below is for h=0.4c and f=0.993Hz */ vel[1] = 2.495*cos(6.2392*time); }

3. compile the source file

4. go to dynamic mesh - zones. i've selected cylinder with rigid body motion with the udf profile just compiled

5. set the BC of the cylinder with moving wall and use the library just compiled.

i wanted to start iteration but the "iterate" button is not highlighted.

so what have i missed out? tks in advance!

  Reply With Quote

Old   September 13, 2006, 11:57
Default Re: problem with oscillating cylinder
  #2
philip
Guest
 
Posts: n/a
You need to initialize your solution. An initial guess is essential for any iterative solver.
  Reply With Quote

Old   September 13, 2006, 20:04
Default Re: problem with oscillating cylinder
  #3
zonexo
Guest
 
Posts: n/a
hi,

tks. initialization worked. however when i tried to preview the mesh, i've got negative volume. from the preview, it's shown that the cylinder at the center's moving, but the other parts are not moving.

what other things must i do? i simply want the whole mesh to move up/down. no mesh deformation is required.
  Reply With Quote

Old   September 14, 2006, 10:13
Default Re: problem with oscillating cylinder
  #4
philip
Guest
 
Posts: n/a
have you gone to Dynamic Mesh...Parameters... and turned remeshing on? You might want to play with the smoothing parameters too if you don't want to remesh.

Make sure you run Fluent from a dos-prompt.

-Philip-
  Reply With Quote

Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
benchmark: flow over a circular cylinder goodegg Main CFD Forum 12 January 22, 2013 12:47
Lift Hysteresis problem in Oscillating Airfoil Farid CFX 3 March 29, 2012 05:52
Oscillating cylinder using icoFoam blowing up rieuk OpenFOAM Running, Solving & CFD 5 September 22, 2010 11:25
[Other] Shadow wall region problem amoolraina ANSYS Meshing & Geometry 0 July 25, 2010 21:17
flow around oscillating cylinder gs Main CFD Forum 0 May 31, 2004 06:34


All times are GMT -4. The time now is 06:34.