IMAGES:

All pictures have been taken by Clement Narteau in September 2011
in the Badain Jaran desert.

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BARCHAN_1:

Note that to generate clear recirculation zones on the hierarchy
of bedforms, we have rescale the dune topography and run the lattice
cellular automaton alone (i.e., without sediment transport).


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BARCHAN_2:

Here, the fieldlines are those that are obtained during
the simulation. Because the stabilization of the flow is
not long enough (i.e., numerical efficiency), we cannot
capture the secondary recirculation on superimposed 
bedforms very well.

Neverthess,  there is a strong drop in shear stress that
explain the development of this superimposed bedform.
You can clearly see that by comparing topography 
(topo_barchan_2.eps) and shear stress (shear_stress_barchan_2.eps).
The small topography generated by the superimposed bedforms
result in a big change in basal shear stress.

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STAR_1:
          topo_star_1.eps = dune topography
	  bed_shear_stress_star_1.eps = bed shear stress on the dune 
	  topo_flow_star_1.eps = Topography + streamlines on the central longitudinal dune slice.

This dune has been generated by coarsening from a flat
sand bed using 5 winds at 0, 72, 144 216, 288 degree.
The resultant flux is null but the time and the angle
between two switches of wind direction are random. 



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STAR_2:
         topo_flow_star_2.eps = Topography + streamlines on the central longitudinal dune slice.

This dune has been generated from a initial conical
sand pile at the center of the system.
We use 5 winds at 0, 72, 144 216, 288 degree.
The resultant flux is null as the time and the
angle between two switches are constant
(72 degree clockwise, 100 t_0).

Note that to generate a nice recirculation zone, we have rotated the
dune of 10 degree and elongate the flat bedrock layer upstream and
downstream.

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