Error while solving for trans-critical fluid flow of N2

sopu · September 5, 2021, 04:11

I am trying to simulate transcritical/supercritical flow of N2.
I am using nasa9 polynomials and transport properties for dense fluids by Chung et al.

I have successfully simulated supercritical flow(T=137K,P=4Mpa) but when I try to go near transcritical region (T=127K,P=4Mpa), the newton rhapson method which calculates temperature back from solved enthalpy fails.

I am attaching the error message here.
https://drive.google.com/file/d/149R...ew?usp=sharing

I have tried few suggestions from FOAM FATAL ERROR Maximum number of iterations exceeded but it doesn't work. This new solver keeps crashing within few minutes.

Please give suggestion to solve this problem.

sopu · November 22, 2021, 02:06

I have changed the root finding algorithm to bisection method and it works now. But it is quite slow due to nature of bisection method.

September 5, 2021, 04:11	Error while solving for trans-critical fluid flow of N2	#1
sopu New Member swapnil Join Date: Feb 2015 Location: India Posts: 5 Rep Power: 11	I am trying to simulate transcritical/supercritical flow of N2. I am using nasa9 polynomials and transport properties for dense fluids by Chung et al. I have successfully simulated supercritical flow(T=137K,P=4Mpa) but when I try to go near transcritical region (T=127K,P=4Mpa), the newton rhapson method which calculates temperature back from solved enthalpy fails. I am attaching the error message here. https://drive.google.com/file/d/149R...ew?usp=sharing I have tried few suggestions from FOAM FATAL ERROR Maximum number of iterations exceeded but it doesn't work. This new solver keeps crashing within few minutes. Please give suggestion to solve this problem.

November 22, 2021, 02:06	Solved this issue by changing algorithm	#2
sopu New Member swapnil Join Date: Feb 2015 Location: India Posts: 5 Rep Power: 11	I have changed the root finding algorithm to bisection method and it works now. But it is quite slow due to nature of bisection method.

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