[DP3103]

Ive been having trouble with the 1d virtual disk model, when i run it im struggling to get the effects of the wake of the turbine when i view velocity magnitude in a scalar scene. Ive also added streamlines and the streamlines are uniform throughout my domain so it is almost as if the simulation is neglecting the virtual disk. Can anyone help please? Thanks

[fluid23]

a picture is worth a thousand words.

also, what settings did you input for the virtual disk?

some context would be helpful.

[DP3103]

I am now getting wake however its not as expected, what settings do you mean i have attached a photo of the velocity magnitude field which is not as expected any ideas why?

[LuckyTran]

That's not the wake from the disk, it's just the flow navigating around the blunt body.

The virtual disk has user inputs; what inputs did you use, if any? If none, then you have a problem.

[fluid23]

Post a screenshot of the model inputs under continua > physics > models.

Also, what are you trying to model?

[DP3103]

Im Trying to get a velocity profile of the domain after the VD to then study the efficiency of the turbine.

[fluid23]

Ok, this is a good start. First thing I would recommend is to double check your inputs. Make sure that velocity, power and thrust tables do not contain some sort of error. Double check the inflow plane, etc..

Next, I would turn on verbosity and display source term and confirm that the disk model is operating and converged by stepping the solution once. You can also confirm and display the source term in scalar scene to confirm that it matches what you would expect.

Finally, I cannot make heads or tails of the tiny image you shared of the wake, so you will have to explain what about your results do not match expectations. It would also be helpful to see your regions setup and understand your domain and boundary conditions.

[DP3103]

I have turned on verbosity for a velocity inlet bc 10m/s. I have attached my results I would expect to see the velocity wake to be blue after the vd downstream and then returning to red a few hundred m upstream but it just stays blue.
All my conditions and set up is attached.

Thanks

[fluid23]

Well, I am not sure what to tell you without looking at the file except that your boundary conditions may need to be further away. Also, your mesh be to coarse at wake/freestream boundary layer to resolve the mixing.

Did you confirm that your thrust and power curves were defined correctly?

Sorry I couldn't be more help.

[DP3103]

No worries by to coarse do you mean the base size should be bigger or smaller. And what do you mean by boundary conditions may need to be further away? Yes thrust and power curves are defined correctly.

Thanks Daniel

[fluid23]

Not exactly. Base size is a mesh control. I am speaking specifically about the size of the cells that exist between the red and blue regions. You need cells that are small enough to resolve the gradients that exist between the wake and external flow.

Can you show a screenshot of a mesh on the plane you are plotting velocity on?

Also, regarding BCs. You want to make sure that your boundary conditions are set far enough away from what you care about that they don't unintentionally influence your results. For example, if the wake isn't dissipating by the time it gets to the pressure outlet, then the outlet may need to be further downstream. Also, having a velocity inlet so close to your inflow plane could be affecting the inflow distribution.

I don't think these things are an issue for your outlet from what you have shown, but it's something to consider in the future.

[DP3103]

I Have managed to sort the above problem however I have been trying to add a velocity profile unsuccessfully.
Basically I want to add the power law velocity profile as a field function vector,

when I add it it says there's a syntax error. the Velocity is changing in the y coordinate i.e. as y increases so does the velocity.

my input is

[0, 12*({Position}/300)^0.28,0]

the equation for the y coordinate is V = KnownV at Known Z * (Z/KnownZ) ^0.28.
my known z is 300 and known v is 12

can you please help thanks

[harishameed33]

Originally Posted by DP3103

I Have managed to sort the above problem however I have been trying to add a velocity profile unsuccessfully.
Basically I want to add the power law velocity profile as a field function vector,

when I add it it says there's a syntax error. the Velocity is changing in the y coordinate i.e. as y increases so does the velocity.

my input is

[0, 12*({Position}/300)^0.28,0]

the equation for the y coordinate is V = KnownV at Known Z * (Z/KnownZ) ^0.28.
my known z is 300 and known v is 12

can you please help thanks

Hi,

I am facing the same problem, not getting the wake as it should be. Could you please tell what exactly you did to solve the issue. Thanks

[harishameed33]

Originally Posted by harishameed33

Hi,

I am facing the same problem, not getting the wake as it should be. Could you please tell what exactly you did to solve the issue. Thanks

I have attached screenshot of the results i am getting