obliquenshock {viadam}R Documentation

Approximate characteristics of an oblique shock

Description

Computes the shock angle, shock thickness, downstream velocity and downstream momentum flux for an oblique shock as functions of deflecting angle and Froude number using an approximation based on the flow against a normal shock with the speed of the normal component of the oblique flow.

Usage

 
obliquenshock(phi,Fr)

Arguments

phi deflecting angle with respect to the direction of steepest decent in a sloping coordinate system aligned with the terrain.
Fr Froude number.

Value

obliquenshock returns a dataframe containing the variables phi (deflecting angle), delta (difference between teta and phi, i.e. width of the stream along the deflecting wall), teta (shock angle), h2ph1 (relative change in flow depth across the shock), u2pu1 (relative change in flow speed across the shock) and h2u2ph1u1 (relative change in momentum flux across the shock). These variables have the same number of elements as teta or Fr. The Froude number and the Froude number normal to the wall are returned as the attributes Fr and Fp of the list.

Note

The angle phi is given in radians and so are all angles that are returned by the function.

This function computes the characteristics of a weak oblique shock. The corresponding strong oblique shock with a (much) larger value of the shock angle teta is eliminated by the approximations used in the derivations of the formulas used. The function obliqueshock may be used to obtain both types of the oblique shock.

The approximations used in this function provide good accuracy for Fr>2.5 and deflecting angles phi somewhat below the maximum deflecting angle which separates the weak and strong shocks for a particular value of the Froude number Fr.

Author(s)

Tomas Johannesson

See Also

obliqueshock and mxphi.

Examples

## Not run: 
obliquenshock(15*pi/180,7)
## End(Not run)

[Package viadam version 0.9 Index]