Differences

This shows you the differences between two versions of the page.

--- dustdevils [2025/03/30 16:55] – admin
+++ dustdevils [2025/04/01 11:56] (current) – admin
@@ Line 1: / Line 1: @@
-=== time history of extremes ===
+===== Dust devils redux =====
+This page shows a revisit to {{ :dustdevils:fiedlerkanak2001.pdf | Rayleigh-Benard convection as a tool for studying dust devils}}, but with the computations done with numerical python.
+It is a substantial upgrade to [[https://12characters.net/dustdevil/ |my old dust devil page]].
+To reproduce these simulations, you may use my ipython notebook:
+[[https://github.com/bfiedler/metr4323/blob/main/N140_convection3d.ipynb|3D convection, periodic]].
+To reproduce the visualizations, you will need {{https://github.com/bfiedler/dustdevils/blob/main/dustdevils.tar.gz | my companion python programs}}.
+In the notebook, in cell number 28, set ''nexp'' to 91:
+<code>
+# choose an integer, see choices for nexp below
+nexp = 91
+</code>
+And then, also in cell 28, you should set tend=40.
+<code>
+elif nexp == 91: # Fiedler and Kanak, 2001
+    ray_over_rayc = 4096
+    hftop = 0
+    gamma = 0
+    wcinc = .3
+    outdir = 'R4096g0w4'
+    xmax,ymax,zmax = 4,4,1
+    #Nx,Ny,Nz= 129,129,33 # the original hi-res
+    Nx,Ny,Nz = 65,65,17 # acceptable level of resolution
+    kp = Nz//8
+    kz = Nz//8
+    neutral_init=True
+    random_init=False
+    anticipated_wmax=4.
+    tend=30.
+    dplot=.1
+</code>
+If you then select 'Run All Cells" for the ipython notebook, the simulation will be complete
+in about 20 minutes (with my i7 chip).  But the simulation for the images here was with the
+hi-resolution, or ''Nx,Ny,Nz= 129,129,33''. With those specs, the simulation may need 5 hours (and 9 GB of disk space).
+In cell 30, the buoyancy is initialized with
+<code>
+bi = .01*np.cos(4*np.pi*xb/xmax) + .01*np.cos(4*np.pi*yb/ymax)
+     + .00001*np.cos(6*np.pi*xb/xmax - 2*np.pi*yb/ymax)
+</code>
+I am not sure why that is apparently different from the idealized choices in Fiedler and Kanak,
+but it makes the point about //symmetry breaking// needed to produce the vertical vorticity of the extreme
+events, which are akin to dust devils.
+==== time history of extremes ====
+Try
+<code>
+./hist.py R4096g0w4 1 400
+</code>
+if all went okay,
+<code>
+./hist.py R4096g0w4 1 40 > R4096g0w4.hist
+</code>0
+And then
+<code>
+./plothist.py -s R4096g0w4.hist
+</code>
+That should produce the following image, which shows a dust devil event just prior to t=30.
 ^{{ :dustdevils:r4096g0w4.png?700 }}^
 | some extreme values at the surface |
-=== vertical vorticity at the lowest level ===
+==== vertical vorticity at the lowest level ====
+<code>
+mkdir pngs
+./npy2contour.py -o pngs R4096g0w4 000001 000400
+./maketitle.py -o titleh.png
+./png2mp4.py pngs/0 -t titleh.png
+</code>
+That will produce ''video.mp4'', showing twin dust devils peaking at t=29.8:
 {{ :dustdevils:wzeta.mp4 |}}
-=== isosurface animation ===
+==== isosurface animation ====
-The extreme event (a.k.a. dustdevil).
+The extreme event (a.k.a. dust devils) in 3-D, with isosurfaces.
+<code>
+mkdir vista
+./npy2vista.py  R4096g0w4 000270 000320 -o vista
+./maketitlevista.py
+./png2mp4.py vista/0 -t titlevista.png
+</code>
 {{ :dustdevils:pzeta.mp4 |}}
-=== Some interactive images at $t=29.8$ ===
+==== Some interactive images at $t=29.8$ ====
+<code>
+./npy2vista.py -s R4096g0w4 000298
+open scene.html
+</code>
 Use your mouse, have fun ...
 {{url>https://12characters.net/rbdd/t298zm40pm2.html}}
 $\zeta=-40$ (purple)   , $p=-2$ (green), and $s$ at the surface
+I did not finish implementing the command line options for ''npy2vista.py'',
+but the source code can be easily edited to select the desired isosurfaces.
+(You may want to copy ''npy2vista.py'' to a file of some other name, and edit that...)
+Change these lines:
+<code>
+#    plotter.add_mesh(contours_w_neg, color="lightblue", opacity=0.5, label="w = -0.5")
+#    plotter.add_mesh(contours_w_pos, color="green", opacity=0.5, label="w = 0.5")
+    plotter.add_mesh(contours_p1, color="green", opacity=0.5, label="p = -2")
+#    plotter.add_mesh(contours_p2, color="purple", opacity=1.0, label="p = -3")
+#    plotter.add_mesh(contours_p3, color="yellow", opacity=.5, label="s =  2")
+#    plotter.add_mesh(contours_p4, color="red", opacity=.5, label="c =  6")
+    plotter.add_mesh(contours_p5, color="purple", opacity=.5, label="$\zeta$ =  -40")
+    plotter.add_mesh(edges, color='black', line_width=3, label="Domain Boundaries")
+    plotter.add_mesh(origin_marker, color="yellow", label="Origin Marker")
+    plotter.add_text(time,color='pink')
+#    plotter.add_mesh(contour_2d, cmap="coolwarm", opacity=0.8, label="2D Contour (p at z=0)")
+    plotter.add_mesh(slice_plane, scalars="s", cmap="OrRd", opacity=1.0, clim=[0,3.0 ])
+</code>
+to
+<code>
+    plotter.add_mesh(contours_w_neg, color="lightblue", opacity=0.5, label="w = -0.5")
+    plotter.add_mesh(contours_w_pos, color="green", opacity=0.5, label="w = 0.5")
+#    plotter.add_mesh(contours_p1, color="green", opacity=0.5, label="p = -2")
+#    plotter.add_mesh(contours_p2, color="purple", opacity=1.0, label="p = -3")
+#    plotter.add_mesh(contours_p3, color="yellow", opacity=.5, label="s =  2")
+    plotter.add_mesh(contours_p4, color="red", opacity=.5, label="c =  6")
+    plotter.add_mesh(contours_p5, color="purple", opacity=.5, label="$\zeta$ =  -40")
+    plotter.add_mesh(edges, color='black', line_width=3, label="Domain Boundaries")
+    plotter.add_mesh(origin_marker, color="yellow", label="Origin Marker")
+    plotter.add_text(time,color='pink')
+#    plotter.add_mesh(contour_2d, cmap="coolwarm", opacity=0.8, label="2D Contour (p at z=0)")
+    plotter.add_mesh(slice_plane, scalars="s", cmap="OrRd", opacity=1.0, clim=[0,3.0 ])
+</code>
+And again:
+<code>
+./npy2vista.py -s R4096g0w4 000298
+open scene.html
+</code>
 {{url>https://12characters.net/rbdd/t298wpm5c6.html}}
 $w=.5$ (green), $w=-.5$ (grey) , $c=6$ (red)
+The suitably renamed ''scene.html'' can then be uploaded to a website, as done here.