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[sbryngelson]

👋 Welcome!

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[FluoPanda96]

Has anyone performed a jet flow simulation using MFC?

[sbryngelson]

It's something like this one https://github.com/MFlowCode/MFC/blob/master/examples/3D_IGR_jet/case.py but @wilfonba might have better details.

[wilfonba]

Here's the case file for that visualization

#!/usr/bin/env python3
import math
import json

pA = 101325
rhoA = 1.29
gam = 1.4
c_l = math.sqrt(1.4 * pA / rhoA)

M = 1.5
pS = 2.458*pA
velS = 0.701*c_l
rhoS = 1.862*rhoA

leng = 1e-2
rJet = leng/8
rC = 2*leng/5
Ny = 999
Nx = Ny * 4.5/3
Nz = Ny
dx = leng / Nx

time_end = 20 * leng / (M * c_l)
cfl = 0.6

dt = cfl * dx / c_l
Nt = int(time_end / dt)

eps = 1e-5

# Configuring case dictionary
print(
    json.dumps(
        {
            # Logistics
            "run_time_info": "T",
            # Computational Domain Parameters
            "x_domain%beg": -2 * leng,
            "x_domain%end": 2.5 * leng,
            "stretch_x": "T",
            "x_a": -1.5,
            "x_b": 1.75*leng,
            "a_x": 10,
            "loops_x": 2,
            "y_domain%beg": -1.5 * leng,
            "y_domain%end": 1.5 * leng,
            "stretch_y": "T",
            "y_a": -1.125*leng,
            "y_b": 1.125*leng,
            "a_y": 10,
            "loops_y": 2,
            "z_domain%beg": -1.5 * leng,
            "z_domain%end": 1.5 * leng,
            "stretch_z": "T",
            "z_a": -1.125*leng,
            "z_b": 1.125*leng,
            "a_z": 10,
            "loops_z": 2,
            "m": int(Nx),
            "n": int(Ny),
            "p": int(Nz),
            # "dt": dt,
            # "t_step_start": 0,
            # "t_step_stop": Nt,
            # "t_step_save": int(Nt / 100),
            "cfl_adap_dt": "T",
            "cfl_target": 0.5,
            "t_stop": time_end,
            "t_save": time_end/100,
            "n_start": 0,
            # Simulation Algorithm Parameters
            "num_patches": 8,
            "model_eqns": 2,
            "alt_soundspeed": "F",
            "num_fluids": 2,
            "mpp_lim": "F",
            "mixture_err": "F",
            "time_stepper": 3,
            "weno_order": 3,
            "weno_eps": 1.0e-16,
            "weno_Re_flux": "F",
            "weno_avg": "F",
            "mapped_weno": "T",
            "null_weights": "F",
            "mp_weno": "F",
            "riemann_solver": 2,
            "wave_speeds": 1,
            "avg_state": 2,

            "bc_x%beg": -17,
            "bc_x%end": -3,
            "bc_y%beg": -3,
            "bc_y%end": -3,
            "bc_z%beg": -3,
            "bc_z%end": -3,

            # Formatted Database Files Structure Parameters
            "format": 1,
            "precision": 2,
            "prim_vars_wrt": "T",
            # "alpha_wrt(1)": "T",
            "parallel_io": "T",
            "file_per_process": "T",

            # Patch 1: Background
            "patch_icpp(1)%geometry": 9,
            "patch_icpp(1)%x_centroid": 0.0,
            "patch_icpp(1)%y_centroid": 0.0,
            "patch_icpp(1)%z_centroid": 0.0,
            "patch_icpp(1)%length_x": 80 * leng,
            "patch_icpp(1)%length_y": 40 * leng,
            "patch_icpp(1)%length_z": 40 * leng,
            "patch_icpp(1)%vel(1)": 0.0e00,
            "patch_icpp(1)%vel(2)": 0.0e00,
            "patch_icpp(1)%vel(3)": 0.0e00,
            "patch_icpp(1)%pres": pA,
            "patch_icpp(1)%alpha_rho(1)": eps*rhoA,
            "patch_icpp(1)%alpha(1)": eps,
            "patch_icpp(1)%alpha_rho(2)": (1-eps)*rhoA,
            "patch_icpp(1)%alpha(2)": 1.0-eps,

            # Jet 1
            "patch_icpp(2)%geometry": 10,
            "patch_icpp(2)%alter_patch(1)": "T",
            "patch_icpp(2)%x_centroid": -2 * leng,
            "patch_icpp(2)%y_centroid": 0,
            "patch_icpp(2)%z_centroid": 0,
            "patch_icpp(2)%length_x": rJet / 2,
            "patch_icpp(2)%radius": rJet,
            "patch_icpp(2)%vel(1)": velS,
            "patch_icpp(2)%vel(2)": 0.0e00,
            "patch_icpp(2)%vel(3)": 0.0e00,
            "patch_icpp(2)%pres": pS,
            "patch_icpp(2)%alpha_rho(1)": (1 - eps)*rhoS,
            "patch_icpp(2)%alpha(1)": (1 - eps),
            "patch_icpp(2)%alpha_rho(2)": eps*rhoA,
            "patch_icpp(2)%alpha(2)": eps,

            # Jet 2
            "patch_icpp(3)%geometry": 10,
            "patch_icpp(3)%alter_patch(1)": "T",
            "patch_icpp(3)%x_centroid": -2 * leng,
            "patch_icpp(3)%y_centroid": 0,
            "patch_icpp(3)%z_centroid": -rC,
            "patch_icpp(3)%length_x": rJet / 2,
            "patch_icpp(3)%radius": rJet,
            "patch_icpp(3)%vel(1)": velS,
            "patch_icpp(3)%vel(2)": 0.0e00,
            "patch_icpp(3)%vel(3)": 0.0e00,
            "patch_icpp(3)%pres": pS,
            "patch_icpp(3)%alpha_rho(1)": (1 - eps)*rhoS,
            "patch_icpp(3)%alpha(1)": (1 - eps),
            "patch_icpp(3)%alpha_rho(2)": eps*rhoA,
            "patch_icpp(3)%alpha(2)": eps,

            # Jet 3
            "patch_icpp(4)%geometry": 10,
            "patch_icpp(4)%alter_patch(1)": "T",
            "patch_icpp(4)%x_centroid": -2 * leng,
            "patch_icpp(4)%y_centroid": 0.0,
            "patch_icpp(4)%z_centroid": rC,
            "patch_icpp(4)%length_x": rJet / 2,
            "patch_icpp(4)%radius": rJet,
            "patch_icpp(4)%vel(1)": velS,
            "patch_icpp(4)%vel(2)": 0.0e00,
            "patch_icpp(4)%vel(3)": 0.0e00,
            "patch_icpp(4)%pres": pS,
            "patch_icpp(4)%alpha_rho(1)": (1 - eps)*rhoS,
            "patch_icpp(4)%alpha(1)": (1 - eps),
            "patch_icpp(4)%alpha_rho(2)": eps*rhoA,
            "patch_icpp(4)%alpha(2)": eps,

            # Jet 4
            "patch_icpp(5)%geometry": 10,
            "patch_icpp(5)%alter_patch(1)": "T",
            "patch_icpp(5)%x_centroid": -2 * leng,
            "patch_icpp(5)%y_centroid": rC*math.sin(math.pi/3),
            "patch_icpp(5)%z_centroid": -rC/2,
            "patch_icpp(5)%length_x": rJet / 2,
            "patch_icpp(5)%radius": rJet,
            "patch_icpp(5)%vel(1)": velS,
            "patch_icpp(5)%vel(2)": 0.0e00,
            "patch_icpp(5)%vel(3)": 0.0e00,
            "patch_icpp(5)%pres": pS,
            "patch_icpp(5)%alpha_rho(1)": (1 - eps)*rhoS,
            "patch_icpp(5)%alpha(1)": (1 - eps),
            "patch_icpp(5)%alpha_rho(2)": eps*rhoA,
            "patch_icpp(5)%alpha(2)": eps,

            # Jet 5
            "patch_icpp(6)%geometry": 10,
            "patch_icpp(6)%alter_patch(1)": "T",
            "patch_icpp(6)%x_centroid": -2 * leng,
            "patch_icpp(6)%y_centroid": -rC*math.sin(math.pi/3),
            "patch_icpp(6)%z_centroid": -rC/2,
            "patch_icpp(6)%length_x": rJet / 2,
            "patch_icpp(6)%radius": rJet,
            "patch_icpp(6)%vel(1)": velS,
            "patch_icpp(6)%vel(2)": 0.0e00,
            "patch_icpp(6)%vel(3)": 0.0e00,
            "patch_icpp(6)%pres": pS,
            "patch_icpp(6)%alpha_rho(1)": (1 - eps)*rhoS,
            "patch_icpp(6)%alpha(1)": (1 - eps),
            "patch_icpp(6)%alpha_rho(2)": eps*rhoA,
            "patch_icpp(6)%alpha(2)": eps,

            # Jet 6
            "patch_icpp(7)%geometry": 10,
            "patch_icpp(7)%alter_patch(1)": "T",
            "patch_icpp(7)%x_centroid": -2 * leng,
            "patch_icpp(7)%y_centroid": rC*math.sin(math.pi/3),
            "patch_icpp(7)%z_centroid": rC/2,
            "patch_icpp(7)%length_x": rJet / 2,
            "patch_icpp(7)%radius": rJet,
            "patch_icpp(7)%vel(1)": velS,
            "patch_icpp(7)%vel(2)": 0.0e00,
            "patch_icpp(7)%vel(3)": 0.0e00,
            "patch_icpp(7)%pres": pS,
            "patch_icpp(7)%alpha_rho(1)": (1 - eps)*rhoS,
            "patch_icpp(7)%alpha(1)": (1 - eps),
            "patch_icpp(7)%alpha_rho(2)": eps*rhoA,
            "patch_icpp(7)%alpha(2)": eps,

            # Jet 7
            "patch_icpp(8)%geometry": 10,
            "patch_icpp(8)%alter_patch(1)": "T",
            "patch_icpp(8)%x_centroid": -2 * leng,
            "patch_icpp(8)%y_centroid": -rC*math.sin(math.pi/3),
            "patch_icpp(8)%z_centroid": rC/2,
            "patch_icpp(8)%length_x": rJet / 2,
            "patch_icpp(8)%radius": rJet,
            "patch_icpp(8)%vel(1)": velS,
            "patch_icpp(8)%vel(2)": 0.0e00,
            "patch_icpp(8)%vel(3)": 0.0e00,
            "patch_icpp(8)%pres": pS,
            "patch_icpp(8)%alpha_rho(1)": (1 - eps)*rhoS,
            "patch_icpp(8)%alpha(1)": (1 - eps),
            "patch_icpp(8)%alpha_rho(2)": eps*rhoA,
            "patch_icpp(8)%alpha(2)": eps,

            # Fluids Physical Parameters
            "fluid_pp(1)%gamma": 1.0e00 / (1.4e00 - 1.0e00),
            "fluid_pp(1)%pi_inf": 0.0,
            "fluid_pp(2)%gamma": 1.0e00 / (1.4e00 - 1.0e00),
            "fluid_pp(2)%pi_inf": 0.0,
            "viscous": "T",
            "fluid_pp(1)%Re(1)": 1.81e5,
            "fluid_pp(2)%Re(1)": 1.81e5,
        }, indent=4
    )
)

[FluoPanda96]

Thank you for sharing the case file!

[FluoPanda96]

In the end of the file it is given that "fluid_pp()%Re()": 1.81e5 . My understanding is that this fluid property is the Real Shear viscosity of fluid (air). This should be 1.81e-5 Pa.s Maybe i understood it wrongly. Could you please clarify what this Re quantity means?

[sbryngelson]

put this in a separate discussion please. thanks!