[aja1345]

Hi,


I am simulating basin solar still using CFX. But I don't know that how to set water level in CFX? The water level inside the basin is 4 cm (in direction of Y).


Thanks.

[AtoHM]

Use a step function inside an expression to initialize the water phase volume fraction below a given spatial coordinate value:
myIniWaterLevel = step(<Offset> - Y Coordinate)
Within the global initialization you can use this expression to give the initial water volume fraction. Also initialize the correct pressure distribution (due to hydrostatic pressure under water).
Define the air volume fraction to be one everywhere else.


There is also a cfx tutorial on this, so you might find a template there.

[aja1345]

Originally Posted by AtoHM

Use a step function inside an expression to initialize the water phase volume fraction below a given spatial coordinate value:
myIniWaterLevel = step(<Offset> - Y Coordinate)
Within the global initialization you can use this expression to give the initial water volume fraction. Also initialize the correct pressure distribution (due to hydrostatic pressure under water).
Define the air volume fraction to be one everywhere else.


There is also a cfx tutorial on this, so you might find a template there.

Thanks. Could you please explain more about "step(<Offset> - Y Coordinate)"?


The water level is between 0 and 0.4 in direction of Y.



I have the following error:

[ghorrocks]

When you are using a CEL function you should look up the documentation (reference manual) so you know the syntax and what it does. You just need to get the syntax right. Also your error message says you need to fix the units - again refer to the documentation on why that is, it is all explained there.

Try myIniWaterLevel = step((y-0.4[m])/1[m])

[aja1345]

Originally Posted by AtoHM

Use a step function inside an expression to initialize the water phase volume fraction below a given spatial coordinate value:
myIniWaterLevel = step(<Offset> - Y Coordinate)
Within the global initialization you can use this expression to give the initial water volume fraction. Also initialize the correct pressure distribution (due to hydrostatic pressure under water).
Define the air volume fraction to be one everywhere else.


There is also a cfx tutorial on this, so you might find a template there.

Which CFX tutorial?

[aja1345]

Now I have following error(but still prior problem is investigating):







Why dose this happen? error mean that it should be define viscosity for glass and wood. But I don't see viscosity in their properties(material tab).


thanks.

[Gert-Jan]

Open the transport properties tab of glass and wood

[Gert-Jan]

Originally Posted by aja1345

Which CFX tutorial?

On the customer portal. If you are a registered user.....

[aja1345]

Firstly I should say that this simulation is steady. About water level, I write expression as flows:

But water volume fraction is as follows. This value of water height is very small. Also, I increased value of waterH (initial water height) but the problem is not solved. How can I solve this problem?












Thanks.

[Gert-Jan]

You mentioned the liquid is 4 cm. So, looks ok. For someone who is not involved in your problem, this can be a completely valid outcome of the simulation. Since you are the only one involved, it is only you who can judge its validity.


So, if you need help, go to your supervisor or describe exactly what you are trying to do, what you expect, what inlet and outlets are, boundary conditions, etc. I have no idea and don't want to guess.

[Gert-Jan]

Also, show your grid.

[aja1345]

Originally Posted by Gert-Jan

Also, show your grid.

Thanks.

[aja1345]

Hi again




I want to allocate glass material to glass boundary (according to the following pic), but I can't do it. In fact, I don't find anything about material in the boundary. How can I solve this problem?












Thanks.

[Gert-Jan]

You can only assign material properties to volumes, not to surfaces.
But why would you include glass? I really wonder:

What question are you trying to answer using CFD?

Do you have this point sharp?

[aja1345]

Originally Posted by Gert-Jan

You can only assign material properties to volumes, not to surfaces.
But why would you include glass? I really wonder:

What question are you trying to answer using CFD?

Do you have this point sharp?

I want to develop a steady three-dimensional, two-phase model for evaporation and condensation processes in solar still by using (CFD) method to simulate the model.

[Gert-Jan]

What you describe is the piece of equipment.
But what question do you have about it?
Is there something wrong with it?
Or do you just perform a CFD calculation to be of the street?

[aja1345]

Originally Posted by Gert-Jan

What you describe is the piece of equipment.
But what question do you have about it?
Is there something wrong with it?
Or do you just perform a CFD calculation to be of the street?

This is a MSC Project and I should valid my work with a paper and then I want to develop this work and investigate different effective parameter on still performance, for example: depth of water(water hieght), glass boundary slip and ...therefore, firstly, I should valid my work.

I solved some problem in this case with help of you and CFD online, But Now I have just one problem and it is depth of water. In fact, I don't know that how can I change this depth with using expression.

Thanks.

[Gert-Jan]

How much is 0.08 [cm]?

[aja1345]

Originally Posted by Gert-Jan

How much is 0.08 [cm]?

Thanks sir, you are right. Value of hieght was not correct
Thanks for your help.