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Flow around Gyrocopter
language   Deutsch Englisch

The flow around a gyrocopter is shown here,   calculated approximately two-dimensionally.   The images were calculated with a 2D-Navier-Stokes-Solver:   For turbulent flow according k,ε - turbulence model,   speed 120 km/h in air at 13 C and 1 bar, discretized in 898 × 241 points and with the boundary conditions:   inflow on the left,   outflow on the right,   slides on top and bottom.

space space A gyrocopter flies over Bremen.

Your browser does not support the video tag.   You can get it from   flying_gyrocopter_x264.mp4  .

  1. The file Bildbereich.png was created with Gnuplot and shows the outline of the gyrocopter in the underlying x,y coordinate system. It covers 974 × 326 pixels,   because the border areas are still present;   the color depth is 24 bits.
  2. The file Kontour-matrix.png was created with Irfanview and Gimp ,   i.e. the edges of Bildbereich.png were cut off, possible remains were covered white, the obstacle area filled black, the color depth reduced to 1 bit b/w. The image file includes 898 × 241 pixels. The image must now be mirrored vertically and saved under the same name.
  3. With XV Kontur-matrix.png was saved b/w as Kontur-matrix.xpm .
  4. The file Kontour-matrix.xpm is loaded into a large editor, e.g. Kate , and saved as Kontour-matrix.txt . All marks outside the matrix are deleted. There are now only the characters
    #
    for fluid and
    .
    for obstacle,   a total of 241 rows and 898 columns.
  5. With the editor Kate all characters
    .
    will be changed in
    0 + blank
    and
    #
    in
    1 + blank
    . Kontour-matrix01.txt has 241 rows and 1796 columns;  
    1
    stands for fluid and
    0
    for obstacle,   separated by one blank.
  6. With the editor Kate all characters in Kontour-matrix01.txt
    1
    will be changed in
    16
    .   The file is saved as tragschrauber.flag and is one input file for the further calculation.
  7. The first calculations showed,   that tragschrauber.flag contains here a total of seven unauthorized obstacle cells. That must be removed, either by deleting the cell or by expanding the obstacle. With Kate all
    16
    in
    I
    are changed, the unauthorized cell is corrected, then all
    I
    in
    16
    for the new flag file.
  8. If you want to check the obstacle area of file tragschrauber.flag , it is recommended to change all
    16
    to blank and save the file as tragschrauber.flag1 . With the command
    a2ps -l500 -o file.ps tragschrauber.flag1
    file.ps is created ,   which can be imported with Gimp and 600 Pixel/in and saved as flagfile.png ;   the obstacle cells are visible as
    0
    on white background.
space space The streamlines were calculated in time intervals of ΔT* = 0.5 ,   d.h. ΔT = ΔT* · L / c = 0.126s and compiled as video. The formation of the Kármán vortex street can be seen.

Your browser does not support the video tag.   You can get it from   gyrocopter_vortex_street_x264.mp4  .

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