What is driving the flow in the 2d hill test case?

[hrishikeshsivanandan]

Hi, I am trying to understand the setup of the em_hill2d_x test case. What exactly drives the flow in this case? There is only an inital sounding of uniform 10m/s in the West-East direction. What boundary condition sustains the flow? In the namelist, 'open_xs = .true.' and 'open_xe = .true.', where do we specify the inflow velocity value of 10m/s?

 

[Ming Chen]

if you look at the the file "input_sounding", you will find that u=10m/s is specified throughout the vertical model levels.

 

[hrishikeshsivanandan]

Thanks! But input_sounding is only for the initial time. What about subsequent times? Unless I'm not understanding something

 

[Ming Chen]

Pleas take a look at the document :

https://www2.mmm.ucar.edu/wrf/users/docs/technote/v4_technote.pdf

Hope this can help you understand the lateral boundary condition of this ideal case and why no subsequent forcing is provided.

 

[hrishikeshsivanandan]

@Ming Chen, is there something specific which you want me to look in there?

 

[Ming Chen]

In chapter 6, pages 53-56, various lateral boundary conditions are described in detail. This will answer your question of lateral boundaries.
The sounding is for initial time, but the normal horizontal velocities along the boundary is specified as the boundary condition.

 

[hrishikeshsivanandan]

In chapter 6, pages 53-56, various lateral boundary conditions are described in detail. This will answer your question of lateral boundaries.
The sounding is for initial time, but the normal horizontal velocities along the boundary is specified as the boundary condition.

Thank you for this @Ming Chen, really appreciate the direction