1D Noh

1D Noh Strong Shock: Currently broken!

This test highlights the ability of a code to track a high Mach number shock. Density is set to 1.0 and pressure to 0.000001 everywhere. For x < 0.5 the velocity is set to 1, while for x > 0.5, velocity is set to -1. Gamma is set to 1.66667. This test was performed with the hydro build (cholla/builds/make.type.hydro) and Van Leer integrator. Full initial conditions can be found in cholla/src/grid/initial_conditions.cppunder Riemann().

Parameter file: (modified from cholla/examples/1D/noh_1D.txt)

Modified to add yl_bcnd, yu_bcnd, zl_bcnd, and zu_bcnd=0. Changed init=Riemann.

#
# Parameter File for Noh Strong Shock test
#

################################################
# number of grid cells in the x dimension
nx=100
# number of grid cells in the y dimension
ny=1
# number of grid cells in the z dimension
nz=1
# final output time
tout=1.0
# time interval for output
outstep=1.0
# name of initial conditions
init=Riemann
# domain properties
xmin=0.0
ymin=0.0
zmin=0.0
xlen=1.0
ylen=1.0
zlen=1.0
# type of boundary conditions
xl_bcnd=3
xu_bcnd=3
yl_bcnd=0
yu_bcnd=0
zl_bcnd=0
zu_bcnd=0
# path to output directory
outdir=./

#################################################
# Parameters for 1D Riemann problems
# density of left state
rho_l=1.0
# velocity of left state
vx_l=1.0
vy_l=0.0
vz_l=0.0
# pressure of left state
P_l=0.000001
# density of right state
rho_r=1.0
# velocity of right state
vx_r=-1.0
vy_r=0.0
vz_r=0.0
# pressure of right state
P_r=0.000001
# location of initial discontinuity
diaph=0.5
# value of gamma
gamma=1.66667

Upon completion, you should obtain two output files. The final density and pressure (in code units) of the solution is shown below, integrated with the Van Leer integrator. Examples of how to extract and plot data can be found in cholla/python_scripts/plot_sod.ipynb.

Note that currently (7/16/2024) this solution does not match that of Liska and Wendroff 2003 (shown below) with either the Van Leer or Simple integration schemes: the center of the density plot does not flatten out, forming a maximum that abruptly drops off at the edges.

Further, the Noh test performs differently upon variation of the output frequency (here, we also vary CFL numbers). Plots made with the simple integration scheme: