Hi,
I'm new to Comsol and i'm trying to model free convection in a prety large domain.
I've realised the model in 2D and it has about 1 square meter and in 3D it has about 0.5 cubic meters.
I'm using 3.5a version and i have found a 2D example of free convection in it's library , example in which the dimension of the domain is a lot smaller by the order of centimeters thing that allows the mesh to be very small about 1e-4 on the heated plate. The example works perfect but when i tried to model my chase it had problems in realising the mesh (out of memory) so i had to build the model ten times smaller using the scale command. The problem is that the results are diferent from reality because of the scale.
My question is if is there a way to model your case at a smaller scale and somehow to obtain results for the real size. I'm thinking at a command or some option to specify that the model is at a certain scale.
And another thing, can you verify the volume force that simulates the force due to changes in density that is (rho0-rho_htgh)*g where rho0 is the density of air at 20 degC which is the initial temperature which gradualy increases (parametric solver).
The example which i was talking about is the heated vertical plate free convection from comsol team.
Another thing is that the heated plate in my case is at an angle (is not vertical like in the model)
The reason why i'm asking if the volume force relation is valid is because using the same conditons i rotated the domain so that the heated plate is horizontal and the air is flowing from left to right in stead of flow from the heated plate up (from down to up).
If someone has any ideea of how i could solve my model please help.
Any information is good. This model bugs me for some time.
Thanks for reading and sorry for all the long writing
All the best,
Viorel
I'm new to Comsol and i'm trying to model free convection in a prety large domain.
I've realised the model in 2D and it has about 1 square meter and in 3D it has about 0.5 cubic meters.
I'm using 3.5a version and i have found a 2D example of free convection in it's library , example in which the dimension of the domain is a lot smaller by the order of centimeters thing that allows the mesh to be very small about 1e-4 on the heated plate. The example works perfect but when i tried to model my chase it had problems in realising the mesh (out of memory) so i had to build the model ten times smaller using the scale command. The problem is that the results are diferent from reality because of the scale.
My question is if is there a way to model your case at a smaller scale and somehow to obtain results for the real size. I'm thinking at a command or some option to specify that the model is at a certain scale.
And another thing, can you verify the volume force that simulates the force due to changes in density that is (rho0-rho_htgh)*g where rho0 is the density of air at 20 degC which is the initial temperature which gradualy increases (parametric solver).
The example which i was talking about is the heated vertical plate free convection from comsol team.
Another thing is that the heated plate in my case is at an angle (is not vertical like in the model)
The reason why i'm asking if the volume force relation is valid is because using the same conditons i rotated the domain so that the heated plate is horizontal and the air is flowing from left to right in stead of flow from the heated plate up (from down to up).
If someone has any ideea of how i could solve my model please help.
Any information is good. This model bugs me for some time.
Thanks for reading and sorry for all the long writing
All the best,
Viorel