Hi, I defined some passive scalars in my model because these donot influence dependant variables and are not part of the solving equations. So I have been assigning them values with: t(is,1+nsc)=value(ip) An error appears while running, it says error#076, negative densities found at more than 100 cells! When I take away this command line of the program, it runs well. These scalars have no direct or indirect influence on the density calculation. I appreciate any help or suggestions Regards, c

If you want to write to the T() array directly like that, you have to make sure that you have allocated the memory correctly, otherwise you will be over-writing memory which STAR is using for something else. Perhaps this memory corruption is the cause of the negative densities. To define the values of a scalar explicitly, it is much better to use the built-in capabilities of STAR: define a passive scalar with "Solution Method"="User". This will activate the SCALFN user subroutine, in which you can specify PHI (the scalar value) for scalar IS in cell IP, as a function of the usual local field values.

hi richard, you are right,the memory was overwriting itself, I tried to define my passive scalars using SCALFN but did'nt work. This is very strange, I defined that in the solution method and specified them to be solved by this subroutine, but it did'nt work. Instead I define the calculation to be done only once per time step, with the following: if(intflg(1).eq.0)then / intflg(2)=-1 / intflg(1)=1 / endif / if(intflg(2).ne.iter) then / coding / intflg(2)=iter / endif. And it worked!! Many thanks C.