[amrrhm]

Hi all,

Attached is top view of a heat exchanger I am trying to simulate. The piston moves downward and pushes the fluid to outlet through the fins. I would like to model only 10 deg (out of 360 degree of the whole geometry) for computational proficiency. I have used zero normal gradient for both pressure and velocity at both sides, but I get the following error:

temperature is greater than max_temp in calc_temp_fraction.

Also I get:
get_temp_from_sensible_sie problem found in rank 83 at cell 34069, located at <0.0215101, 0.020375, 0.122875 >, in region 0, whose level=10, ii=910, jj=473, kk=737

and the time steps decreases dramatically and it says: time-step limited by temperature extrapolation error, recovering

I am not sure if this error is related to the boundary condition or not. It would be appreciated if you would help me about this error and also let me know if the zero normal gradient is the proper BC for my purpose.

Thanks

[xieshengbai]

Hello,

First of all, temperature extrapolation error indicates something wrong in the energy solver, which can be caused by many reasons, such as poor grid resolution, wrong boundary conditions, improper spray model setup, etc. Since the error message gives you the location of the error spot, you can visualize it in STUDIO to figure out where exactly it is and what might be the cause.

Second, what type of boundary do you set for the sides? I don't quite understand what you meant by "zero normal gradient for both pressure and velocity". Does it suggest as inlet and outlet conditions (which I don't think is correct)? Instead, since you are using a sector, if the swirl motion is weak, you can use periodic bc there. Please make sure that the geometry and triangulation on the two sides are identical if the periodic bc is used.

If you still have troubles, please feel free to contact with us at support@convergecfd.com.

Originally Posted by amrrhm

Hi all,

Attached is top view of a heat exchanger I am trying to simulate. The piston moves downward and pushes the fluid to outlet through the fins. I would like to model only 10 deg (out of 360 degree of the whole geometry) for computational proficiency. I have used zero normal gradient for both pressure and velocity at both sides, but I get the following error:

temperature is greater than max_temp in calc_temp_fraction.

Also I get:
get_temp_from_sensible_sie problem found in rank 83 at cell 34069, located at <0.0215101, 0.020375, 0.122875 >, in region 0, whose level=10, ii=910, jj=473, kk=737

and the time steps decreases dramatically and it says: time-step limited by temperature extrapolation error, recovering

I am not sure if this error is related to the boundary condition or not. It would be appreciated if you would help me about this error and also let me know if the zero normal gradient is the proper BC for my purpose.

Thanks

[amrrhm]

Thanks for your response, The periodic BC solved the problem.

[Ahamed]

I was running the case setup file for Internal_Combustion_Engines/ Heavy_Duty_Diesel/ Engine_sector_Diesel_CTC by changing the application type from crank-based to time-based and making the piston at rest to just see the fuel-drop interaction. I got error "temperature is greater than max_temp in calc_temp_fraction." I am stuck here.I have also attached the cvg file.

I was wondering if you could provide me a guidance on this. Your help will be highly appreciated.