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October 27, 2018, 14:05 |
Moving a wall at a frequency
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#1 |
New Member
Kimster
Join Date: Oct 2018
Posts: 9
Rep Power: 7 |
Hi,
I am new to Fluent. I am trying to oscillate a wall at a certain frequency in the horizontal direction. It is a circular tube that I am trying to oscillate and see the effect of the lift and drag forces on the adjacent tubes at different flow velocities of water. Some people have told me about UDFs. I don't know how to do that. If there is an easier way please let me know or please walk me through creating a UDF. Appreciate your help. kind regards, CFD noob. |
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October 29, 2018, 14:18 |
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#2 |
Senior Member
Lucky
Join Date: Apr 2011
Location: Orlando, FL USA
Posts: 5,675
Rep Power: 66 |
Is the oscillation parallel to the flow? I.e. is there any squeezing effect?
You can just apply a time-dependent velocity to the wall. The velocity can be applied as a udf or even simpler a csv style profile. |
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October 29, 2018, 22:54 |
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#3 |
New Member
Kimster
Join Date: Oct 2018
Posts: 9
Rep Power: 7 |
Hi,
I've managed to start compiling UDFs without any issues now. Took me two days to get it working. Appreciate if someone can share a UDF for oscillating a cylinder in cross flow at a certain frequency from its current location. There is no squeezing effect. Thanks |
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October 29, 2018, 23:04 |
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#4 |
New Member
Kimster
Join Date: Oct 2018
Posts: 9
Rep Power: 7 |
Hi,
I've managed to start compiling UDFs without any issues now. Took me two days to get it working. Appreciate if someone can share a UDF for oscillating a cylinder in cross flow at a certain frequency from its current location. There is no squeezing effect. Thanks |
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October 30, 2018, 00:27 |
Udf
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#5 |
New Member
Kimster
Join Date: Oct 2018
Posts: 9
Rep Power: 7 |
Hi,
This UDF is working but the cylinder moves to the right and comes back to same position, therefore is oscillating about a point towards the right of the origin point of the cylinder. I want it to oscillate right and left from its current location. How would I change this code? Please help. /* Moving Grid problem - CG movement of a cylinder */ #include "udf.h" static real velx = 0.0; DEFINE_CG_MOTION(cylinder, dt, vel, omega, time, dtime) { NV_S(vel, =, 0.0); NV_S(omega, =, 0.0); velx = 0.005 * sin(3.1415927 * time / 5.); vel[0] = velx; } |
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