[kingjewel1]

I've been reading in the literature about modeling atmospheric boundary layers that a constant shear stress equal to rho*U_max^2, should be applied to the upper ceiling if you like as well as making it free slip. Hargreaves and Wright say this helps to maintain a homogeneous logarithmic profile throughout the domain. So... How do you do it?

In fluent for example I add a momentum source term to thw first layer of cells below theupper boundary layer and set it that way. How about openfoam? Is therre a like for like way of doing this? Or is there a different way?

Cheers,

[cristopf]

Hey,

I tried the ABL in OF by myself some time ago. Did you find a solution how to initialize a fixed shear stress at the upper boundary in the meantime? I didn´t know how to do that and what value you have to assume. Cause like Hargreaves and Wright figured out it´s important to keep the log profile more or less constant over the length (especially k was affected).

Greeting
Christof

[HPE]

Might the following be related:

ENH: Improve and verify atmBoundaryLayerInlet conditions including "tutorials/verificationAndValidation/atmosphericFlows/HargreavesWright_2007"

    top                                                                            
    {                                                                              
    //  (HW:p. 365):                                                               
    //  "In addition, as suggested by RH and often ignored by others, a"           
    //  "constant shear stress of rho*(u^*)^2 was applied at the top boundary." 
    //                                                                             
    //  u^* ~ uRef*kappa/ln((zRef+z0)/z0)                                          
    //  (HW:Table 1):                                                              
    //  uRef = 10 m/s                                                              
    //  zRef = 6 m                                                                 
    //  z0 = 0.01 m                                                                
    //  tau = rho*(u^*)^2 = 0.390796574                                            
        type            fixedShearStress;                                          
        tau             (0.390796574 0 0);                                         
        value           uniform (0 0 0);                                           
    }