Attached here you can find 3 JPG files,In 1f.JPG you can see the simulation of the shell side only.It shows correct static pressure distribution for air (maximum at inlet and minimum at outlet).n2f.JPG shows the results when the shell and coil sides are simulated together. The thermal oil pressure distribution is correct, however, in 2fRescaled.JPG you can notice how the air pressure distribution becomes incorrect!nI used 2 ways to simulate the combined model:nFirst, by creating a conformal mesh for the whole model including (air, thermal-oil and solids) .nSecond, by creating 2 separate meshes for thermal-oil and air then defining coupled interface between them.nboth ways use the same settings defined in the main post and both of them generate the same problem!nn