Default BC not taken correctly?

Question

Hi Chris and Hi everyone

I noticed something strange in AEM3D debug file. I have set the default_bc to 6 which means “free slip walls, and drag bottom” but once I run the model I get the following message:

NOTE: DEFAULT_BC is SLIP_SIDES_NOSLIP_BTM
 
  ***** WARNING **** WARNING **** WARNING **** WARNING ****
 * SPEED not simulated so ignoring input in datablock file
 *********************************************************

Considering the technically different meaning of "No slip" and "Bottom Drag" in this model, this means that the model takes no bottom Cd and considers the bottom as No_slip anyway (Speed is not simulated as an output parameter then).

Is it really not simulated or is just a debugging issue?

Cheers,

Behnam

Answer 1

Hi Behnam,

It looks like the manual is incorrect here.  The values in the code are

NOSLIP_ALL             = 1
FREESLIP_ALL         = 2
DRAG_ALL               = 3
SLIP_SIDES_DRAG_BTM    = 5
SLIP_SIDES_NOSLIP_BTM  = 6
TBBL                   = 9

I'll correct the manual.

Thanks for pointing this out.

Chris

Comments

Hi Chris,

Thanks for your help. How about the "speed" parameter simulation? I suppose it is the current speed. Is it simulated only in certain circumstances? Because it is not simulated once I set the default_bc to 5. (I am coupling the water quality module with the hydrodynamic module.)

---

HI, speed is never simulated.  You need to calculate it from U and V velocity.

HydroHub will do this for you for sheets.

Chris