Changes between Version 52 and Version 53 of doc/tec/bc

Timestamp:

Nov 19, 2018 1:23:10 PM (6 years ago)

Author:

suehring

Comment:

--

doc/tec/bc

@@ -358 +358 @@
 Hence, as a compromise, length scales are set to 8 time the minimum grid spacing. 
 
-
-Note, for ''z''>''z,,i,,'' the components of the stress tensor are set to zero so that effectively no synthetic turbulence is imposed above the boundary-layer height.
+Note, for ''z''>''z,,i,,'' the components of the stress tensor, length- and timescales are set to zero so that effectively no synthetic turbulence is imposed above the boundary-layer height (also saving computational costs). 
  
-method 2 undergoes testing
-
-At this point we emphasize that this method only generates turbulence which is statistically correlated. Large coherent structures such as e.g.  hexagonal pattern as typically observed in a convective boundary layer, however, cannot be generated by this method. So far, turbulence is only added to the three wind components. No perturbations are added to the subgrid-scale turbulent-kinetic energy and potential temperature.
-
-If switched on, the turbulence generator imposed turbulent fluctuations on all lateral boundaries with Dirichlet boundary conditions for the velocity components. For example, if the offline nesting is switched on, where all four lateral boundaries are non-cyclic, the turbulence generator applied at all lateral boundaries. 
+'''Please note, method 2 currently undergoes extensively testing.'''
+
+At this point we emphasize that using the turbulence generator from [#xie2008 Xie and Castro (2008)] only generates turbulence which is correlated in space and time but not necessarily generate realistic turbulent structures as they occur in the real world. Large coherent structures such as e.g. hexagonal pattern as typically observed in a convective boundary layer, however, cannot be generated by this method. 
+Further, we want to add that turbulence is only added to the three wind components. No perturbations are added to the subgrid-scale turbulent-kinetic energy and potential temperature.
+
+If switched on, the turbulence generator imposed turbulent fluctuations on all lateral boundaries with Dirichlet boundary conditions for the velocity components. For example, if the offline nesting is switched on, where all four lateral boundaries are non-cyclic, the turbulence generator applied at all lateral boundaries, even though a lateral boundary is also an outflow boundary layer. 
 
 == Open outflow boundary conditions ==