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Convergence of a huge model (10km) - bore hole heat echanger
Posted 20.08.2016, 04:28 GMT-4 Fluid & Heat, Heat Transfer & Phase Change Version 5.2 0 Replies
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I am trying to simulate 2D time dependent study of vertical borehole heat exchanger using non-isothermal pipe flow and heat transfer in solids. My model consists of rectangular which resembles the rock and 1D pipe. Water flows through the pipe from the surface to the bottom of the heat exhanger, it heats up on the way, because the temperature increases with the depth in th rock. The rock cools down as the heat transfers from the rock to the water. I have tried simulations with 5 km deep exchanger, everything worked great. However, now I amd trying to simulate 10 km one, with the same parameters, (except for the depth) and I cant manage to converge this one. I have tried to:
1. Increase density of mesh, up to a computing capabilities of my PC
2. Run steady state pre-run of the flow in pipe and then use this output as input in time dependent study
3. Increase the limit of iterations in solver to 100
Nothing worked, it is not converging and it always returns an error: failed to find consistent initial values.
I think that the only problem is the size of the exchanger and limit of the computing power. Could you help me please? How you would overcome this problem?
Thank you very much
Marian
Hello Marian Mojoko
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