Hi Mr Rob I finally managed to get reasonable results, just wanted to update you with how i solved the problem, might be useful to others.
The curve below is the pressure difference between 2 cross sections in a horizontal pipeline, transporting oil and water in the stratified flow regime.
the circular inlet is split into two halves (upper for oil, lower for water).
i did not include any turbulence fluctuations at inlets (didnt use vortex method or spectral synthesizer), this solved the problem of bursting pressure values.
But could you explain to me why? In ansys documentation, it is recommended adding artificial turbulence at inlets when using LES.
Also when i use ELES, at the RANS/LES interface i add the vortex method and results are perfect.
Best regards Peter