Learning Forum

[antoinel]

When running the simulation, I received the floating point exception error - divergence detected in AMG solver: uds-0. I increased the time step, improved the mesh, changed the stabilization method to BCGSTAB. None of these changes eliminated the error. What is causing this error? How do I fix this error?

[Keyur Kanade]

this will need lot of more information. 

what is mesh quality. min ortho quality?

are you using uds?

udf?

what is application?

etc

[antoinel]

Below is the information for mesh and minimum orthogonal quality:

Mesh Quality:

Minimum Orthogonal Quality = 2.65119e-01 cell 4180 on zone 3 (ID: 133071 on partition: 5) at location ( 1.20276e-01 1.03184e-01 1.01707e-01)

 

Maximum Aspect Ratio = 1.40132e+01 cell 4180 on zone 3 (ID: 133071 on partition: 5) at location ( 1.20276e-01 1.03184e-01 1.01707e-01)

 

I am using a uds. I am not using a udf.

 

I am modeling the anisotropic UDS diffusivity of a fluid within a domain, where the XX, XY, XZ, YY, YZ, and ZZ matrix components are 1e-6, 5e-8, 4.5e-8, 9.58e-7, 4.2e-8, and 9.82e-7, respectively. The diffusivity and the density are 1000. I am initializing the simulation at a specific source term and then running the simulation for  72000 steps, 10 iterations each step with a time step size of .1 s. The simulation fails at a flow time of 2752.4 s. 

[VidushiUCT]

Could you solve it? I am having the same issue and trying to find an answer.

[Karthik Remella]

Hello,

When the solver shows the floating point exception error, what does the contour plot of your UDS look like? Also, are you making sure that your solution is converging every time-step?

Could you please help us understand when you get this error - at the beginning of the simulation or in the middle?

Thank you.

Karthik

[faiq01]

Hello everybody, nI am using three User defined scalars to track blood form three inlet towards two outlets to find the percent distribution of blood reached from each inlet at two outlets.nI specified values for each UDS = 1 at their respective inlets and use diffusion coefficient = 3.2*10-5 kg/m2 sec (diffusion coefficient of blood in blood). Sources term was taken to be zero and at outlet Flux was set to 0. Convective terms were set to mass flow rate and non-steady term to none.nWhen I run the simulation it gives me error after running simulation for two seconds ( No of iteration = 700) divergence detected in uds-2 floating point exception.I want to know what could be the possible cause of divergence boundary conditions at inlets and outlet, diffusion coefficient or mesh quality. nScreen shots of residuals are attached.Thanks in advancennFaiqnn

[Rob]

What do the results look like? Ie where is the problem region, and what's going on there (flow etc)?n

[K Abhilash]

I am using battery model for simulation while initiatiating the simulation iam getting this error. Can you help with a appropriate solution