I have noticed some strange effects in my total temperature and I believe it may be due to the effect of artificial viscosity introduced by the solver. I was wondering if anyone out there has had a similar experience or could give me some pointers on this. Thanks!

Please explain what artificial viscosity you are referring to? I mean, what is modeling the viscosity, and why is it unrealistic.

Give more details to your problem, then there will be more to discuss.

thank you for your comments, I am relatively new to CFD so I'm probably asking something quite obvious! I am modelling compressible flow, of air from a volume/atmosphere into a bellmouth ended pipe. I was expecting to see little or no heat transfer and as a result was expecting my total temperature to remain fairly constant. This is the case with the segregated solver but with the coupled solver I get an unexpected temperature variation, not only is it larger than expected it is also in a region where the bellmouth should have no influence. I have been trying to get to the bottom of it unsuccesfully. Artificial viscosity was suggested to me as a possibility. As the approach to linerizing and solving the discretised equations is different in the coupled and segregated solvers, I thought this odd behaviour might be a product of the numerical method. I'm quite stuck on this and would appreciate if you could give me any advice! Thanks