Learning Forum

[NiteshDubey]

I have loaded a UDF for the spatial variation of viscosity in my simulation. I am getting these errors. Need the help of experts. Any help will be highly appreciated.

 

My UDF is:

 

/*********************************************************************

UDF that simulates  spatially dependent viscosity property

**********************************************************************/

#include "udf.h"

#define a 20105467790.5412

#define b 2.692576799425

#define c 5083.56137738767

#define d -84995.6051593393

#define e -2230225.26461472

#define f 852890049.062181

#define g 502636694.742164

 

DEFINE_PROPERTY(cell_viscosity, cell,thread)

{

real mu;

real y, z;

real ZB[ND_ND];

C_CENTROID(ZB,cell,thread);

 

y=ZB[1];    /* y cooridnate*/

z=ZB[2];    /* z cooridnate*/

 

mu=1.21 - 2.71*(a + b*(z-0.006) + c*pow(z-0.006,2.) + d*pow(z-0.006,3.) + e*pow(z-0.006,4.) + f*pow(z-0.006,5.) + g/(y+0.52347)) + 

25.46*pow((a + b*(z-0.006) + c*pow(z-0.006,2.) + d*pow(z-0.006,3.) + e*pow(z-0.006,4.) + f*pow(z-0.006,5.) + g/(y+0.52347)),2.);

return mu;

 

}

 

I did the following checks:

 

1.  Mesh quality is good

2.  Discretization scheme is second-order for momentum and pressure. For gradient, it is least-squares cell-based.

 

 

Divergence detected in AMG solver: x-momentum Stabilizing y-momentum to enhance linear solver robustness.

 

Divergence detected in AMG solver: y-momentum Stabilizing z-momentum to enhance linear solver robustness.

 

Divergence detected in AMG solver: z-momentum Stabilizing pressure correction to enhance linear solver robustness.

 

Divergence detected in AMG solver: pressure correction

Divergence detected in AMG solver: x-momentum

Divergence detected in AMG solver: y-momentum

Divergence detected in AMG solver: z-momentum

Divergence detected in AMG solver: pressure correction

Error at host: floating point exception

 

 

Error at Node 0: floating-point exception

Error at Node 1: floating-point exception

 

===============Message from the Cortex Process================================

 

Compute processes interrupted. Processing can be resumed.

 

==============================================================================

 

Error: floating point exception

 

Error Object: #f

 

 

[Rob]

Plot the function in Excel and see how it looks. Whenever I see coefficients with that many significant figures I always expect the curve to be very different to what you're expecting. 

Also remember that UDFs use SI units: your coordinates are in metres regardless of the units in your model.