CMS-Flow:Bottom Friction: Difference between revisions

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'''Flow with Waves'''
'''Flow with Waves'''


In the case with waves, the bottom friction is calculated as
In the case with waves, the bottom friction is calculated with the generalized formula


       <math> \tau_m = \lambda \tau_c  </math>
       <math> \tau_m = \lambda_{wc} \tau_c  </math>
 
where <math> lambda_{wc} </math> is the nonlinear wave enhancement factor which varies depending on the model selected. There are five models available in CMS.
 
''1. Simplified Quadradric Formula''
 
in this case the enhancement factor is equal to
 
      <math>\lambda_{wc} = \sqrt{ u_c^2 + c_w u_w^2 } / u_c </math>

Revision as of 19:27, 5 May 2010

Bottom Friction

Flow without Waves

In the situation without waves, the bottom shear stress is calculated based on the quadratic formula

     

where is the bottom friction coefficient, is the depth-averaged current velocity.

Flow with Waves

In the case with waves, the bottom friction is calculated with the generalized formula

     

where is the nonlinear wave enhancement factor which varies depending on the model selected. There are five models available in CMS.

1. Simplified Quadradric Formula

in this case the enhancement factor is equal to