Learning Forum

[Annie Liang]

Trying to simulate multiphase water liquid-vapour flow through a channel where one wall has a heat flux of 1.31 MW/m2, heating water liquid into vapour way above the saturation temperature. The inlet temperature of the liquid is 310 deg celsius and the vapor temperature is assumed to be equal to the saturation temperature (~340 deg) throughout the channel. I am using the Eulerian RPI boiling model and have set a constant saturation temperature which I have hand-calculated from steam tables at the specified pressure (147 bar). I found that the residuals diverge when I solve the simulation, leading to a point exception error.

I think this error occurs when the liquid temperature increases above saturation as when I only remove the heat flux boundary condition, there's no error and the residuals converge. Also, the residuals converge when I set the saturation temperature in the multiphase model to a high value (so that the specified heat flux doesn't change the liquid's phase). This has given me the confidence to say that the saturation temperature is causing the convergence issues but I have no idea how to resolve this. Does anyone know how to resolve this?

[Annie Liang]

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[Rob]

Depending on the wall temperature you might be trying to boil too much liquid at once. How is vapour temperature being set?