Q) I am using the Boussinesq approximation and although the fluid heats up the density does not change.
I have set the thermal expansivity to 0.00011. Do you have any suggestions as to what I should do?
A) When you use Bossinesq, the density change due to thermal expansion is just put in as source terms. i.e. the actual density does not change.
If you want to see the true density change then you can either:
1) Run it as you have and then create a variable in CFXPost to be the true density and add the density change as an expression.
2) or given the relation that the density is a function of thermal expansion coefficient and delta T, put this relationship in for the density. To do this, use an expression remembering to not toggle the 'density depends on' box.
Q) I am using the Boussinesq approximation and although the fluid heats up the density does not change. I have set the thermal expansivity to 0.00011. Do you have any suggestions as to what I should do? A) When you use Bossinesq, the density change due to thermal expansion is just put in as source terms. i.e. the actual density does not change. If you want to see the true density change then you can either: 1) Run it as you have and then create a variable in CFXPost to be the true density and add the density change as an expression. 2) or given the relation that the density is a function of thermal expansion coefficient and delta T, put this relationship in for the density. To do this, use an expression remembering to not toggle the 'density depends on' box. 

