Changes between Version 15 and Version 16 of u/erica/ExactRiemannSolver


Ignore:
Timestamp:
01/04/13 23:24:05 (12 years ago)
Author:
Erica Kaminski
Comment:

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  • u/erica/ExactRiemannSolver

    v15 v16  
    77Given the above properties of the Riemann problem, an algebraic expression can be derived which gives p in the central "star-region" (denoted by '*'). The overall structure of the Riemann problem then is to solve this algebraic equation for p*. Once p* is known, u* follows immediately. The remaining rho*_L and rho*_R follow from expressions valid for the specific L- or R- wave present.
    88
    9 Specifically, this means that the code will determine at every point (x,t), that point's relative position to the different waves present. Once the position is determined, the solution is given by analytic expressions for the following five possibilities: pre- or post- shock, ahead of rarefaction head, behind rarefaction tail, or within the rarefaction fan. The position of each sampling point (x,t) is determined by a characteristic speed in the grid given by s = dx/t, where dx is the distance from the initial discontinuity to the sampling point (x,t), and t is the simulation end time.
     9Specifically, this means that the code will determine at every point (x,t), that point's relative position to the different waves present. Once the position is determined, the solution is given by analytic expressions for the following five possibilities: pre- or post- shock, ahead of rarefaction head, behind rarefaction tail, or within the rarefaction fan. The position of each sampling point (x,t) is determined by a characteristic speed in the grid given by s = dx/t, where dx is the distance from the initial discontinuity to the sampling point (x,t), and t is the simulation end time. This s for every point on the grid can be compared to the known present waves, as their speeds are known exactly. In this way, the relative position of the sampling point with respect to the waves on the grid is determined.
    1010
    1111The program thus will consist of 4 parts: 1. Code to find p* using an iterative process, 2. Comparing p* to p_L and p_R to identify the types of nonlinear waves present in the solution, 3. Find remaining quantities in star region, where u* is given by simple expression in Toro (eqn. 4.9), and wave-specific expressions give rho*_L and rho*_R.