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January 9, 2013, 05:39 |
udf for wall slip
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#1 |
New Member
ammm
Join Date: Nov 2012
Posts: 21
Rep Power: 13 |
i need a udf for slip wall
i want to use udf for setting this boundary condition: us=B*(du/dy) what should i do? |
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January 10, 2013, 01:49 |
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#2 |
Senior Member
SSL
Join Date: Oct 2012
Posts: 226
Rep Power: 14 |
I have already written it. Email me please.
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January 10, 2013, 05:02 |
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#3 |
New Member
ammm
Join Date: Nov 2012
Posts: 21
Rep Power: 13 |
i emailed you thank you in advance
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January 12, 2013, 12:58 |
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#4 |
New Member
Farzad Ahamdi
Join Date: Feb 2012
Location: Iran
Posts: 4
Rep Power: 14 |
Dear Mr Sadeghi
I also have written a UDF for slip velocity which works correctly, but when I want to add the term due to thermal creep, I get the below error: "FLUENT received fatal signal (ACCESS_VIOLATION)." I recognized that this error is due to using the expression "C_T_G(cell,t)" in my UDF. Could you help me to solve this problem? Thank you so much! |
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January 12, 2013, 23:26 |
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#5 | |
Senior Member
SSL
Join Date: Oct 2012
Posts: 226
Rep Power: 14 |
Quote:
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January 15, 2013, 09:19 |
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#6 |
New Member
ammm
Join Date: Nov 2012
Posts: 21
Rep Power: 13 |
i write this udf for slip. is it correct???
#include "udf.h" DEFINE_PROFILE(shear_stressx, thread, n) { face_t f ; cell_t c0 ; Thread *t0 =THREAD_T0(thread) ; float u0,uw,vderivate, sstressx ; begin_f_loop(f, thread) { c0 = F_C0(f ,thread) ; vderivate= C_DUDY(c0,t0) ; u0 = C_U(c0, t0); uw=u0+1*pow(10,-6)*vderivate ; F_U(f, thread)=uw; sstressx = -.001003*vderivate ; F_PROFILE(f,thread,n) = sstressx ; } end_f_loop(f,thread) |
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January 16, 2013, 04:49 |
How to write a slip condition in wall
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#7 |
New Member
Jetica
Join Date: Jan 2013
Posts: 1
Rep Power: 0 |
dear Mr Sadeghi and ammm:
i need a udf(fluent or cfx is ok) for slip wall.As ammm metioned,the slip wall which can be attached with thermal creep is the best.But if the thermal creep is excluded,that is ok. could you send me a udf you have writtern.please send the email:asm23374634@gmail.com thank you very much |
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January 17, 2013, 05:03 |
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#8 |
New Member
ammm
Join Date: Nov 2012
Posts: 21
Rep Power: 13 |
my udf works good with low slip length but for larger slip length not converged. Can anyone guide me for this convergence problem?
i use fluent 6.2 and when i dont use udf it works corrctly please help me |
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February 22, 2013, 16:10 |
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#9 | |
New Member
Join Date: Aug 2011
Posts: 8
Rep Power: 14 |
Quote:
All of these operations is due to suitable initializations which help Fluent to start a solution from a rather logic guess. each UDF produces a sudden jump in the resodual graph, so it's better avoiding 3 jumps at the same time, instead, imply them gradually. |
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February 25, 2013, 04:32 |
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#10 | |
Super Moderator
Alex
Join Date: Jun 2012
Location: Germany
Posts: 3,399
Rep Power: 46 |
Quote:
Apply some under-relaxation. Additionally, I can only emphasize once more that fluent comes with a BC of the type us=B*(du/dy). It is called "Slip Boundary Formulation for Low-Pressure Gas System" and even includes the term for thermal creep. |
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February 25, 2013, 23:44 |
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#11 |
Senior Member
SSL
Join Date: Oct 2012
Posts: 226
Rep Power: 14 |
I have done that before without thermal creep, but today have found how to consider thermal creep also.
It needs step by step enabling and disabling equations. |
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March 4, 2013, 05:34 |
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#12 |
New Member
Katerina
Join Date: Jul 2012
Posts: 2
Rep Power: 0 |
Dear all,
I'm doing a simulation with slip and VOF. I would like to define slip - shear stress for liquid only. But I'm doing it wrong. My shear stress=mu*dudx*vof What should I change to get C_VOF for correct thread ? #include "udf.h" DEFINE_PROFILE(wall_shear_y,thread,position) { face_t f; Thread *t0, *t2, *t3; cell_t c0; double TAUxy, mu; double dudx; double vof; begin_f_loop(f,thread) { t0=THREAD_T0(thread); /*adjacent cell index*/ c0=F_C0(f,thread); /*adjacent cell thread*/ t2 = THREAD_SUB_THREAD(t0, 0); // take ID of phase no.1 t3 = THREAD_SUB_THREAD(t0, 1); // take ID of phase no.2 dudx=C_DUDX(c0,t0); mu=C_MU_L(c0,t0); /*viscosity*/ begin_c_loop(c0,t3) { vof=C_VOF(c0,t3); /*volume of fluid value in adjacent cell for phase 2*/ } end_c_loop(c0,t3) TAUxy=mu*dudx*vof; F_PROFILE(f,thread,position)=TAUxy; } end_f_loop(f,thread) } Regards, Katerina |
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March 26, 2014, 04:41 |
slip wall shear
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#13 |
New Member
elaf
Join Date: May 2013
Posts: 15
Rep Power: 12 |
I was wondering if any one can help me?
I am using flow around rotating cylinder, the shear stresses at the wall need to be specified to constant value. In this option, there are 3 components for the shear stresses, i.e. x direction components and so on. Does anyone know for example how can set these values for cylinder surface Regard. Last edited by elaf_2003; March 26, 2014 at 12:52. |
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November 13, 2014, 04:25 |
hi
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#14 |
Member
Qureshi M Z I
Join Date: Sep 2013
Posts: 79
Rep Power: 12 |
hi, i need a UDF for slip boundary condition at the bottom of the domain or at the ground (wall), 3D case is just like a flow over a building. if anybody have sample UDF please share this, z is a vertical axis of my domain. thanks
mziqureshi@hotmail.com regards, |
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May 15, 2017, 03:19 |
UDF Slip Rotational Wall
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#15 |
New Member
Widhi
Join Date: May 2017
Posts: 1
Rep Power: 0 |
Hi,
i need the udf for slip rotational wall. in this case i want to simulate for 2-d journal bearing. what should i do? Thanks. |
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June 22, 2017, 04:30 |
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#16 | |
New Member
tae won
Join Date: Jun 2017
Posts: 1
Rep Power: 0 |
Quote:
Hi I'm doing about micro-channel problem. so I need the udf(fluent) for slip condition for slip wall. if you have udf of slip condition and temperature jump condition. Could you send me the udf code? It doesn't matter if it not include thermal creep my email : ssdssdblack@naver.com thank you |
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March 26, 2018, 06:49 |
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#17 |
New Member
Syed umer tirmizi
Join Date: Mar 2018
Posts: 4
Rep Power: 8 |
Can you send me the udf file for us=b*(du/dy) model .
Email :syedumer46@gmail.com Last edited by tirmizi; March 26, 2018 at 06:51. Reason: email entering |
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March 28, 2018, 04:58 |
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#18 |
New Member
golf du
Join Date: Oct 2010
Posts: 2
Rep Power: 0 |
Would you please mail me the udf, thanks a lot! My e_mail is 4963404@qq.com
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March 28, 2018, 05:10 |
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#19 |
Senior Member
Join Date: Nov 2013
Posts: 1,965
Rep Power: 26 |
I hope anybody reading this is aware that low pressure boundary slip is for a long time already included in Fluent, without needing to add any UDFs. Look for "low pressure boundary slip" in the manual to find out more.
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February 13, 2019, 10:03 |
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#20 |
New Member
Pratik Manna
Join Date: Feb 2019
Posts: 1
Rep Power: 0 |
Dear Mr. Sadeghi
Can you mail me the UDF? I, require this UDF for a simulation of flow through a micro-channel. My e-mail is - bishaktomanush@gmail.com regards S. G. Das |
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