I am not familiar with MSC.Dytran, so if someone who is familiar with this code could answer this.

Could dytran be used for model of fluid flow where the fluid is of very high viscosity (and viscous effects could not be neglected).

As I understood from their manual, it seems it could only solve Euler equations.

Any comments????

judging by the number of responses posted so far, one would say that most readers of this forum are not familiar with that programme, me included. I logged on their web site and tried to get any clues, in their on line documents one notice the use of the term "Eulerian domain" so often. This is a rather technical way of talking or referring to a fixed control volume in space, but it does not mean that they are solving the Euler equations. You can check the panel where the fluid properties are introduced, is there an entry for the fluid viscosity. Of course you can talk to their support engineers and definitely they will be glad to help you.