UDF for changing viscosity

July 27, 2006, 03:51

hello i want to increase 100 times the viscosity in a pipe, but just in a region of a circular pipe ( for avoiding turbulence problems)that it is to mean to maintain the viscosity in the first meter of the pipe and increase it in the rest is it possible? how can i do that? i assume that it is with an UDF... Thanks very much

July 31, 2006, 15:03

Hi

Yes, you have write a UDF for that by using the DEFINE_PROPERTY macros wherein you can indicate that the velocity changes with position.

Hope it helps Shanti

vsampath · October 28, 2009, 16:59

Hi this is my UDF

#include "udf.h"

DEFINE_PROPERTY(cell_viscosity,cell,thread)
{
cell_t c;
real x[ND_ND];
real mu_lam;
real y;
Thread *t;
C_CENTROID(x,c,t);
y= x[1];
mu_lam= 0.001002*(2-(y/0.01));
printf("MU= %f \n",mu_lam);
return mu_lam;

}

MY Problem is i get the value of mu at only same y i need to define value of mu at different y coordinates ..... can someone help me rectify this out??

July 27, 2006, 03:51	UDF for changing viscosity	#1
Rafael Guest Posts: n/a	hello i want to increase 100 times the viscosity in a pipe, but just in a region of a circular pipe ( for avoiding turbulence problems)that it is to mean to maintain the viscosity in the first meter of the pipe and increase it in the rest is it possible? how can i do that? i assume that it is with an UDF... Thanks very much

July 31, 2006, 15:03	Re: UDF for changing viscosity	#2
shanti Guest Posts: n/a	Hi Yes, you have write a UDF for that by using the DEFINE_PROPERTY macros wherein you can indicate that the velocity changes with position. Hope it helps Shanti

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
writin udf for non-newtonian viscosity	zolfaghari	FLUENT	0	September 19, 2007 06:32
viscosity in UDF!	denhan	FLUENT	0	April 6, 2007 02:12
subgrid turbulent viscosity for UDF in LES	David TAIEB	FLUENT	0	April 2, 2007 09:27
VISCOSITY UDF	AdN	FLUENT	0	May 23, 2006 06:33
Help - UDF for solid shear viscosity	nbh2801	FLUENT	0	April 21, 2006 08:49

October 28, 2009, 16:59		#3
vsampath New Member Vivek Sampath Join Date: Oct 2009 Location: Houston Posts: 6 Rep Power: 17	Hi this is my UDF #include "udf.h" DEFINE_PROPERTY(cell_viscosity,cell,thread) { cell_t c; real x[ND_ND]; real mu_lam; real y; Thread t; C_CENTROID(x,c,t); y= x[1]; mu_lam= 0.001002(2-(y/0.01)); printf("MU= %f \n",mu_lam); return mu_lam; } MY Problem is i get the value of mu at only same y i need to define value of mu at different y coordinates ..... can someone help me rectify this out??