Spring, 2019
Jewett
 Computer Program #6 -- Test E
 ATMS 502 / CSE 566
Numerical Fluid Dynamics

Test E:  Colliding outflows -- 2D test of 3D code

  • Domain and execution:
    • 33x33x16 grid - runs quickly for interactive testing
    • (note odd dimension for nx,ny; initial bubble at exact X-Y center)
    • ∆x=∆y=∆z = 500 meters
    • ∆t = 1.0 seconds; run to 450s
    • Save data (via putfield) at 150, 250, 350 and 450s (and other times if you wish).
  • Physics:
    • All processes retained and active. 
    • Sound speed Cs=100 m/s.
    • Non-monotonic piecewise linear advection.
    • Diffusion coefficients = 50 (momentum), 5 (temperature).
  • Initial condition:
    • Theta: 2 thermals:
      • -20˚, center (    250,8250,4250)
      • -20˚, center (16250,8250,4250)
      •  radius = 4000m in each direction X and Z, 999999 meters in Y to create ~2D initial condition
    • U,W: are initially zero - no perturbations on U
    • V (using same formula as for theta) has -25 m/s max perturbation for "left boundary thermal", and +25m/s on right.
  • Boundary conditions:
    • Usual (symmetric X, periodic Y, 0-gradient Z)

Test E:  Colliding density currents

  • This is a 2-D test of your 3-D code.  Without U perturbations, it is a 2D initial state, and the solution should remain 2D.  In particular, when evaluating your solution you should look for any evidence of along-line (i.e. in Y-direction) variation to your fields, and you should also find no noise on the periodic Y boundaries.  I have omitted Y-Z plots below for obvious reasons, but you can compute them -- they should show only height variation (in plotted Y-Z slices).
  • Text output from running my code may be found here.

  • Contour intervals in plots below are 1˚ (for theta), 5 m/s (for U,V,W), 20 hPa (for P'), and 100 (for vorticity; is actually x10-4 s-1).
  • The 3-D plots use plot3d's default "eye" for viewing (you look towards ~ -X).  The isosurface for theta' = -10K, and for vorticity = 100.
  • Plot3d will compute vorticity for you (and thus allow you to plot it), provided you have called putfield with your U-wind
    component named "U" and V-wind component named "V" -- in your call to putfield from your main program.
  • As noted elsewhere in the program 6 pages, you can use plot3d with a script to generate all the plots you want, at once.
    The script I used for the plots below is available here, named doplot.  To use it, copy it to Stampede, tell the system it is an executable script by typing the somewhat arcane Unix command chmod ugo+x doplot, and run it by typing "doplot" as you would any other program.  You will see doplot contains the same text you would enter by hand to see the fields.  When it finishes you should have a series of ncar metacode files (e.g. Vort_xy.meta).  You could then run metagif to convert their contents to GIF. 
  • It is also possible to put all plots in a single metacode file; see the Running Plot3d page for an example of doing so ... you could then make all the plots into GIFs and combine them in a zip file to move to your PC with the single command

    ~tg457444/502/Tools/metagif  filename.meta -all -zip [or, use -tar for a TapeArchive file; most PCs will work with either .tar or .zip]

    Or, if you wanted a single file of all images saved as a movie, use

    ~tg457444/502/Tools/metagif  filename.meta -all -gifmovie [or, -qtmovie for Quicktime]

    Note either command will leave a pile of .gif files sitting in your directory. 
    metagif will tell you the file names it is using when making movies.

  • I created an animation of theta by doing the following.  I ran my program, saving output via putfield every 10 seconds (i.e. every 10 steps in this case).  The RunHistory.dat file was 16039292 bytes.  I then ran plot3d as usual, plotting T in 3-D with a -10˚ isosurface, and I used metagif to convert the resulting metacode file into a series of GIFs and movies in animated GIF and Quicktime form.  You can see my login session for the details of what I typed and the resulting output.  The theta animations are here: GIF, QT.


Test E		 T=0 T=150 T=250 T=350 T=450
T
X-Z
T
X-Y
k=1
T
3-D
Vorticity
X-Z
Vorticity
X-Y
k=1
Vorticity
3-D
U
X-Z
U
X-Y
k=1
V
X-Z
V
X-Y
k=1
W
X-Z
W
X-Y
k=3
P
X-Z
P
X-Y
k=1