Pipe flow module / Falied to evluate variable Jacobian

I am working over a simple pipe flow problem, where I encountered with an Jacobial Error saying ;

Failed to evaluate variable Jacobian.
- Variable: mod1.nipfl.u3
- Geometry: 1
- Boundary: 7 10 13

I request you to kindly help me.

This is a coupled HT and Isothermal pipe flow problem, where three straight pipes are used to cool the structure. I think, I am facing problem with the initial value i.e. Tangential velocity for which I don't know the sifnificance of it niether it is explained with the mold cooling module ( example model )

Please see the Jpeg Image.

PFA



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Ishant Jain
R&DSS, TSL, Jamshedpur