Description
Return a local Lax-Friedrichs/Rusanov-style numerical flux.
A simulation update combines supplied states, fluxes, forces and time conventions. Local integration and interface terms can be evaluated independently, while a full solver must also supply consistent fields, boundary conditions, conservation and convergence behavior.
Return a local Lax-Friedrichs/Rusanov-style numerical flux.
When to use this tool
Use Riemann Flux Supplied Wave Speed Factor when checking one explicitly supplied integration, flux or lattice-population contribution.
How to use the tool and how it works
- Enter leftState, rightState, leftFlux, rightFlux, maxWaveSpeed. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read centralFlux, dissipation, numericalFlux. Use the output convention below.
Return a local Lax-Friedrichs/Rusanov-style numerical flux. Require maxWaveSpeed >= 0; centralFlux = (leftFlux+rightFlux)/2, dissipation = speed*(rightState-leftState)/2, numericalFlux = central-dissipation.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| leftState | Left State | Required. Finite number. |
| rightState | Right State | Required. Finite number. |
| leftFlux | Left Flux | Required. Finite number. |
| rightFlux | Right Flux | Required. Finite number. |
| maxWaveSpeed | Max Wave Speed | Required. Finite number; minimum 0. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| centralFlux | Central Flux | Required. Finite number. |
| dissipation | Dissipation | Required. Finite number. |
| numericalFlux | Numerical Flux | Required. Finite number. |
{
"input": {
"leftState": 1,
"rightState": 3,
"leftFlux": 2,
"rightFlux": 6,
"maxWaveSpeed": 2
},
"output": {
"centralFlux": 4,
"dissipation": 2,
"numericalFlux": 2
}
}Limitations and assumptions
- The maximum wave speed and physical fluxes are supplied; no Riemann solution, stability bound or conservation-law system is verified.
- Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.
Alternative or Complementary methods
Use and validate the complete numerical method with its state initialization, boundary conditions and physical model for a reliable simulation.
References
Similar or alternative tools
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