[KGRAAT]

I am a novice Star-CCM+ 10 user who has formal training in ANSYS Fluent. I am completing collaborative research into the free-stream effects on the heat transfer coefficient from a flat plate. The first step is to model and confirm turbulence decay in a rectangular fluid domain of 4x1x1 m.

The domain has been meshed using hexahedral solid elements of size h=0.02m. The front face is a velocity inlet with U=4m/s a turbulence intensity of 10% and an integral length scale of 100mm. The back wall is a pressure outlet and the four remaining walls are slip boundaries.

The k-e RANS model is to be used and confirmed against the power law decay model for grid generated turbulence. I have successfully used ANSYS Fluent to model the decay and have confirmed the results to be correct, but when I use the same parameters and the same model constants in Star-CCM+, I get a result with incorrect turbulence decay (see the graph attached comparing the correct ANSYS Fluent result with the Star-CCM+ result). The data has been extracted using a line probe of 200 points through the centre of the domain.

I have meticulously checked all the models, constants, the mesh etc. against my Fluent studies and have not found a reason why they are different; everything between them is the same except the solution methods. I have read through the Star-CCM manual, but still have been unable to understand why there is a difference.

Any help would be appreciated

Kyle