Hypersonic Viscous Interaction
This module exposes functionalities to estimate the hypersonic viscous interaction over a flat plate, in which for large Mach numbers and small Reynolds numbers the attached viscous flow is no more of boundary-layer type. Instead, observation shows that past a flat plate, a very large surface pressure is present just downstream of the leading edge, which is in contrast to high-Reynolds number boundary-layer flows, where the surface pressure is the free-stream pressure.
- pygasflow.atd.viscous_interaction.chapman_rubesin(Tw, Tinf, func=None)[source]
Compute the Chapman-Rubesin factor (linear viscosity-law constant).
- Parameters
- Twfloat or array_like
Temperature at the wall.
- Tinffloat or array_like
Free stream temperature.
- funccallable
Function to compute the viscosity. If None (default value), a power law viscosity will be used.
- Returns
- outfloat or array_like
See also
- pygasflow.atd.viscous_interaction.interaction_parameter(Minf, Re_inf, Cinf=1, laminar=True)[source]
Compute the viscous interaction parameter, Chi, which correlates pressure changes.
- Parameters
- Minffloat or array_like
Free stream Mach number.
- Re_inffloat or array_like
Free stream Reynolds number computed at some location. If a unitary Reynolds number is provided, then the unitary interaction parameter will be returned.
- Cinffloat or array_like
Chapman-Rubesin linear viscosity-law constant.
- laminarbool
Default to True. Set
laminar=Falseto compute the viscous interaction parameter for turbulent flow.
- Returns
- outfloat or array_like
See also
- pygasflow.atd.viscous_interaction.rarefaction_parameter(Minf, Re_inf, Cinf)[source]
Compute the rarefaction parameter, V, which correlates viscous/inviscid-induced perturbations in the skin friction and heat transfer.
- Parameters
- Minffloat or array_like
Free stream Mach number.
- Re_inffloat or array_like
Free stream Reynolds number computed at some location. If a unitary Reynolds number is provided, then the unitary interaction parameter will be returned.
- Cinffloat or array_like
Chapman-Rubesin linear viscosity-law constant.
- Returns
- outfloat or array_like
See also
- pygasflow.atd.viscous_interaction.critical_distance(Chi_u, weak=True, cold_wall=True, Chi_crit=None)[source]
Compute the critical distance, x_crit.
In a flat plate:
For x < x_crit there is strong interaction.
For x > x_crit there is weak interaction.
- Parameters
- Chi_ufloat or array_like
Unitary viscous interaction parameter.
- weakbool, optional
Selector to decide the value of Chi_crit.
- cold_wallbool, optional
Selector to decide the value of Chi_crit.
- Chi_critNone or float, optional
Specify a numerical value to Chi_crit. This overrides
weakandcold_wall.
- Returns
- outfloat or array_like
See also
- pygasflow.atd.viscous_interaction.wall_pressure_ratio(Chi, Tw_Tt, weak=True, laminar=True, gamma=1.4)[source]
Compute the pressure ratio Pw / Pinf between the pressure at the wall and the free stream pressure.
- Parameters
- Chifloat or array_like
Viscous interaction parameter.
- Tw_Ttfloat or array_like
Temperature ratio between the temperature at the wall and the free stream temperature.
Set
Tw_Tt=0to specify a cold wall.Set
Tw_Tt=1to specify a hot wall.
- weakbool
Default to True indicating a weak interaction. Set
weak=Falseto specify for a strong interaction.- laminarbool
Default to True. Set
laminar=Falseto compute the pressure ratio for a turbulent flow.- gammafloat
Specific heats ratio. Default to 1.4. Must be \(\gamma > 1\).
- Returns
- outfloat or array_like
- pygasflow.atd.viscous_interaction.length_shock_formation_region(Vu, coeff=0.1)[source]
Compute the length of the shock formation region.
- Parameters
- Vufloat or array_like
Unitary rarefaction parameter.
- coefffloat or array_like
A coefficient indicating the departure from the strong interaction region. It goes 0.1 for the surface pressure, to 0.3 for the heat transfer. Default to 0.1.
- Returns
- outfloat or array_like
See also
References
“Criterion for slip near the leading edge of a flat plate in hypersonic flow”, L. Talbot, 1963