Initial condition problem: epsilon calculation

[TheodoreGalanos]

Hi @mostaphaRoudsari

I think I may have found the reason for the problems people have been facing with running the outdoor studies.

At the moment it seems our epsilon value is miscalculated. I have checked various different initial velocities and it is a recurring issue. I also went over Ji's case reported here http://www.grasshopper3d.com/forum/topics/butterfly-doesn-t-work-with-opefoam-v1606?groupUrl=ladybug&groupId=2985220%3AGroup%3A658987&id=2985220%3ATopic%3A1574828&page=1#comments and found the same thing.

Manually changing initial conditions to the ones calculated from the formulas we have set in conditions.py allows the simulations to work normally once again.

One test case I tried had:

Zref = 10 m
Uref = 6.23 m/s.
z0 = 0.005

The initial turbulence conditions set by BF were:

k = 0.349
epsilon = 0.827

The fact that epsilon is higher than k initially gave me suspicion smth is up here. The actual values calculated with our formulas should be:

k = 0.349 (BF calculates it correctly)
epsilon = 0.00968

Could it be that this line:

epsilon = _Uabl ** 3 / self.k * (self.Zref + self.z0) is supposed to be this:

epsilon = _Uabl ** 3 / (self.k * (self.Zref + self.z0))

Not sure though since even then the result would not be the one reported by BF (0.827). Do you think you can trace this?

Kind regards,
Theodore.

[mostaphaRoudsari]

@TheodoreGalanos thank you for finding the bug. I can't find the original calculation formulas. Can you share them with me again. Adding the pranthesis still gives me a wrong value of 0.00826.

[mostaphaRoudsari]

Nevermind! I found it: #24 I will double check and will let you know the results.

[mostaphaRoudsari]

@TheodoreGalanos the formulas that I have doesn't generate 0.00968. Once you send me your formulas I can do a comparison and figure it what is going wrong here.

[TheodoreGalanos]

I found them in conditions.py

But that is the thing I couldn't figure out myself. Adding the parenthesis would still give a different number from what BF is creating. I even tried using k instead of κ but still not that value.
Perhaps there is some other calculation somewhere?

[mostaphaRoudsari]

@TheodoreGalanos did you check the new version? Can we close this issue now?

[mostaphaRoudsari]

It is fixed via 15cb9e4