[sparta-users] Stagnation Streamline Unpopulated in Axisymmetric Simulation

[Brown, G. P. <bro...@pu...>]

Dear SPARTA mailing list,

I am learning how to use SPARTA for summer research and have been doing some initial cases in order to learn the program. I put together an input file for an axisymmetric sphere at 90 km in air with a freestream velocity of 14 km/s, which I have included below. I am interested in analyzing the stagnation streamline, which to my understanding would lie on the ylo boundary. However, using the emit/face xlo command did not seem to populate this region with any particles, as the dump file returned null grid calculation values along the ylo boundary. 1) Does SPARTA have the ability to accurately simulate the stagnation streamline in the axisymmetric setup, and 2) if it does, how do I get SPARTA to populate the bottom row of grid cells while maintaining a uniform, straight flow from the xlo boundary?
Input File:
seed                    1111
dimension         2

boundary          o ao p

create_box               -7.5 7.5 0.0 10 -0.5 0.5
create_grid              1125 750 1
balance_grid             rcb cell

global                  nrho 6.243.e19 fnum 5.54933.e14

species                 air.species N2 O2 N O NO
mixture                 air N2 O2 N O NO vstream 14000 0.0 0.0 temp 191.7
mixture                 air N2 frac 0.7837578
mixture                 air O2 frac 0.204069
mixture                 air N frac 1.736345e-9
mixture                 air O frac 0.0032276
mixture                 air NO frac 0.0

read_surf         data.circle origin 5 5 0 &
                    trans -5 -5 0 scale 0.3333 0.3333 1 clip

surf_collide            1 diffuse 298 0.9
surf_modify             all collide 1


collide                 vss air air.vss
collide_modify        vibrate smooth
react                   tce air.tce

create_particles air n 0

fix               in emit/face air xlo

timestep          1e-6

stats              100
stats_style       step cpu np nattempt ncoll nscoll

collide_modify vremax 100 yes

run 5000

fix fadapt adapt 20 all refine coarsen particle 45 15

run 10000

unfix fadapt

collide_modify vremax 0 yes

compute           c1th thermal/grid all air temp press
compute           c1grid grid all air n nrho u v trot tvib
fix                f1grid ave/grid all 1 10000 10000 c_c1grid[*] c_c1th[*] ave running
dump               d1grid grid all 100000 grid_air_90km_14kms_test5.*.dat xlo ylo f_f1grid[*]

compute          c2grid grid all species nrho nfrac
fix               f2grid ave/grid all 1 10000 10000 c_c2grid[*] ave running
dump              d2grid grid all 100000 grid_20_species_90km_14kms_test5.*.dat xlo ylo f_f2grid[*]

dump              3 image all 100000 image_test5.*.ppm type type pdiam 0.1 &
                   surf proc 0.005 &
                   size 720 720 axes yes 0.9 0.02 particle yes gline yes 0.0001 zoom 2.0
dump_modify             3 pad 4
run 2000000
 
Apologies if this is an obvious error/mistake, and thank you in advance,

Graham Brown
---------------------
Purdue University Class of 2023
Aeronautical and Astronautical Engineering
bro...@pu...
031663530