negative fluid temperature

Ya13 · May 4, 2016, 11:13

I am simulating a powder (using a sphere fluid region) radiated and heated by a laser beam. the beam source is added in qsadd.f in which I modified rhoe. But the simulation is terminated reporting 'negative fluid temperature'. I check the cell index with negative fluid temperature, and find that the cell is often near the surface in the void region. Anyone can help me? thanks

Ya13 · May 4, 2016, 11:21

By the way, I find that if I change the powder into a plate, simulation is OK. So I guess that the problem may relate to the geometry. But I can hardly find the exact cause nor manage to deal with it.

asmaahassan21366 · May 4, 2016, 17:31

Please , do you know how can i dissapear the negative signs of veloicty in the results of fluent ??

hamedsheikh · January 31, 2024, 03:44

Quote:

Originally Posted by Ya13

By the way, I find that if I change the powder into a plate, simulation is OK. So I guess that the problem may relate to the geometry. But I can hardly find the exact cause nor manage to deal with it.

Hi
I also have the same problem and I changed and replaced a qsadd.F file in Flow-3d software v 11.0.4. But the software does not call the code. I wanted to see if anyone could provide me with the Gaussian distribution heat source code that works?
I will be very grateful.

Dan H · March 12, 2024, 19:51

I had a similar issue where my simulations terminated reporting 'negative fluid temperature'. I was applying a heat flux to a surface. In my case, all of the negative temperatures were associated with cells that had very small fluid fractions (<0.00001). I was able to fix the problem by only applying heat flux to cells above a certain fluid fraction.

hamedsheikh · March 16, 2024, 18:26

Quote:

Originally Posted by Dan H

I had a similar issue where my simulations terminated reporting 'negative fluid temperature'. I was applying a heat flux to a surface. In my case, all of the negative temperatures were associated with cells that had very small fluid fractions (<0.00001). I was able to fix the problem by only applying heat flux to cells above a certain fluid fraction.

Dear Dan H,
I have sent you a private message. Please consider it. Thank you very much.

May 4, 2016, 11:13	negative fluid temperature	#1
Ya13 New Member Ya Qian Join Date: Mar 2016 Posts: 6 Rep Power: 10	I am simulating a powder (using a sphere fluid region) radiated and heated by a laser beam. the beam source is added in qsadd.f in which I modified rhoe. But the simulation is terminated reporting 'negative fluid temperature'. I check the cell index with negative fluid temperature, and find that the cell is often near the surface in the void region. Anyone can help me? thanks

March 12, 2024, 19:51		#5
Dan H New Member Dan Hawker Join Date: Mar 2024 Posts: 2 Rep Power: 0	I had a similar issue where my simulations terminated reporting 'negative fluid temperature'. I was applying a heat flux to a surface. In my case, all of the negative temperatures were associated with cells that had very small fluid fractions (<0.00001). I was able to fix the problem by only applying heat flux to cells above a certain fluid fraction. hamedsheikh likes this.

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May 4, 2016, 11:21		#2
Ya13 New Member Ya Qian Join Date: Mar 2016 Posts: 6 Rep Power: 10	By the way, I find that if I change the powder into a plate, simulation is OK. So I guess that the problem may relate to the geometry. But I can hardly find the exact cause nor manage to deal with it.

May 4, 2016, 17:31		#3
asmaahassan21366 New Member Asmaa Hassan Abdelhamid Join Date: Apr 2016 Posts: 2 Rep Power: 0	Please , do you know how can i dissapear the negative signs of veloicty in the results of fluent ??