density current
 

dear friends,
I am going to model density current made by temperature change in a channel of water flow. the model is in 2D and one phase of water fluid.
how can I do it?
first I did a transient model which water flows in 20c and then after it reaches stable condition I changed the temperature to 25c but the flow density didn't changed and density currents didn't form.
did I make something wrong?
best regards