My problem is to simulate a number of wall diffusers. At this stage the diffusers are assumed to be fully opened and modeled with inlet velocity BC. Special attention was given to the mesh in the region of interest.

When checking my results the inlet velocity at the opening is two times less than the specified value?? Something should be wrong!!

Any suggestion will be appreciated

Note: The solution is semi-converged at this stage

Near the end of the RESULT file is a secton headed 'Nett source'. This reports the sources calculated for each source patch. The R1 sources are mass sources in kg/s. You can check if the mass source associated with your inlet object is as expected (area*inlet velocity*inlet density). The sources reported for U1,V1 & W1 and momentum sources with units of N. You can check that the momentum source associated with the inlet object is the mass-source for that object times the inlet velocity.

You should also bear in mind that the inlet is in effect on the back face of a cell, but the velocity printed in RESULT is on the front face. It is quite possible for fluid to leave the cell through the other four faces, not just the one opposite the inlet face.

If you cannot satisfy yourself that all is as it should be, send your Q1 and RESULT file to support@cham.co.uk and they will look at it for you, as long as you have a valid support contract.