[oliveira1820]

I´m modelling water/steam (IAWPS) phase change with Thermal Phase Change Model and even with 600 W distributed in only a 3 cm cone, the max temperature I obtain it isn´t enough to form steam. The recipient after equilibrium only presents liquid water as ~100 % volume fraction.

I can´t undesrtand what´s happening. Does anyone had a similar problem?

[ghorrocks]

Either you have not put enough heat into the water to boil it or you have a numerical error which is grossly underestimating the heat transfer. It would detailed analysis of your simulation to work out which, and the forum is not the place to do that sort of thing.

If you posted your geometry and output file we can have a look at your setup and see if we can see any obvious problems.

[oliveira1820]

I´l start by posting my heat source, I want it to be distributed with different values for each cylinder (to simulate bragg peak heat deposition from a cylinder energy beam), resulting in the sum of 639 W:

The recipient has the referencial at x=0, y=0 and z=0. I consider the cylinder along the z direction.


This is my CEL:

valorx = abs(x)
valory = abs(y)

limitxy = 0.0045 [m] #cylinder radius

sourcex = if (valorx < limitxy, 1, 0)

sourcey = if (valory < limitxy, 1, 0)

limitz1 = 0.0025[m] # different consecutive cylinders range
limitz2 = 0.011[m]
limitz3 = 0.0155[m]
limitz4 = 0.02[m]
limitz5 = 0.02225[m]


sourcez1 = if (z<limitz1, 1, 0)
sourcez2 = if( z>limitz1, if (z<limitz2, 1, 0) , 0)
sourcez3 = if( z>limitz2, if (z<limitz3, 1, 0) , 0)
sourcez4 = if( z>limitz3, if (z<limitz4, 1, 0) , 0)
sourcez5 = if( z>limitz4, if (z<limitz5, 1, 0) , 0)


sourcetotal1 = sourcex*sourcey*sourcez1
sourcetotal2 = sourcex*sourcey*sourcez2
sourcetotal3 = sourcex*sourcey*sourcez3
sourcetotal4 = sourcex*sourcey*sourcez4
sourcetotal5 = sourcex*sourcey*sourcez5

Sourcefluido = (sourcetotal1*106.65+ sourcetotal2*114.18 + sourcetotal3*114.49 + sourcetotal4*125.04 + sourcetotal5*178.64) [kg m^2 s^-3] #Total Source applied to my full domain with different energy for each one


END


The recipient has initially 80% liquid water and 20% steam, the source is a Bulk Source (Use Volume Fraction) (Total Source).

Does it seem good for you? Do the 639 W get deposited this way evenly in both fluids (considering the olume fraction inside each cylinder) in each cylinder and 639W summed?

[ghorrocks]

You don't need to do all that stuff if you just define a mesh region then define that mesh region as a subdomain which you apply your source to.

You should check that your source term results in 639W of heating as you intend. Check that the temperature is rising at the expected rate.

I cannot answer your other questions without seeing your geometry as I have no idea what you are modelling.

[oliveira1820]

I´l try to do the cylinders as mesh regions and apply a source to each one and I´l comeback with feeedback

I need to design the areas on AutoCad first right?

[ghorrocks]

The easiest way is to define them as separate regions in the mesh. So you might be able to do that in your meshing package, or you might need to do it in your solid modelling package depending on your setup.

[oliveira1820]

But I have a doubt, if I design a cubic domain and then cylinders inside the cube. How can I say to the software that the cylinders are sub-domain of the cubes to make the sources in the cylinders, and the water just exist in the cube? Because if I consider all on the same domain, the space ocupied by the cylinders overlaps with the cube and software end in error, cause water is on both twice.

Or is it another way of telling the software that I want the source inside the cylinders, that is using only cylinders geometry as reference to the energy sources, and ignore them o the rest.

[ghorrocks]

The solids must not overlap. So if you generate cylinders in the middle of your domain you must remove those cylindrical regions from the outer region.