Learning Forum

[jzliuyu]

Hi, everyone, 

I am working on a case of laminar flow of a viscous liquid in a cylinder. The rheological model of the liquid can be written as follows:

The Udf I wrote is as follows:

#include "udf.h"

#include "mem.h"

DEFINE_PROPERTY(cell_viscosity,cell,thread)

{

#if 

real tau0=10;

real a=20;

real b=5;

real gamma = C_STRAIN_RATE_MAG(cell,thread);        

real mu_lam;                                    

mu_lam=tau0/gamma+a+b*pow(gamma,2);

returnmu_lam;

}

However,  I found it does not work in Fluent (Ansys 2019 R1) and the following message is shown in Console window:

Error: floating point exception

Error Object: #f

Can anybody tell me what is wrong with my UDF?  

[DrAmine]

You might use for viscosity a standard value on the beginning. Consider that in your UDF.

[Rob]

When you interpret/compile the code what errors do you see? If there aren't any does the model run with a fixed viscosity?