Temperature discontinuity with Species Transport

Dominique

Hello,

I am getting strange results with FLUENT when I am modeling Species transport without reaction.

I have 2 parallel velocity inlets, each from a different gas that are mixing in a reactor. So I use the Species Transport option (without reaction) and I defined my mixture accordingly (I also defined the properties of both gases since I am using the mixing-laws because I do not know the properties of the mixture)

First, I wanted to simulate the resulting flow without any heat source.

Strangely, in the mixing area (between both inlets), FLUENT is calculating a temperature difference...even if everything is at a constant temperature and I even removed the option of "Diffusion Heat source" in the definition of my Species model. Normally, no temperature gradient should occur since ALL temperatures are constant and NO heat source are present (and all temperature change due to diffusion are NOT included).

Anyone knows where does this discontinuity comes from? (For a constant temperature of 193.15K, there appears a different of about +/- 10K (and that's without the interpolation for the visualisation)

Thanks