Thermophoretic effect
 

I have ran a series of isothermal simulations. Particles are injected in a 2-D flow over a flat plate, and the particles that hit the plate have been counted.
Now, I want to run the experiments with a temperature gradient, to study thermophoresis. The problem is that so far, the results are exactly the same as for the isothermal conditions. I would appreciate some input on what may cause this?
My settings:
Models:
Multiphase: off
Energy: on
Viscous - standard k-e, Enhanced Wall Fn
Radiation - off
Species - species transport
discrete phase - on
solidification & melting - off
acoustics - off

Under the discrete phase->edit:
physical models: thermophoretic force + pressure gradient force.
In injections, T=673.15K
The temperature of the surface of interest is 573.15K, all other walls are 673.15K
At the solution initialization, the temperature is also set to 673.15K.