Modified Wavenumber Analyzer

Compare dispersion and numerical damping of upwind, central, and QUICK-like differences on a kh curve.

visual calculatorNumerics & Stability

Read the flow shape before trusting the number.

This page turns a CFD setup into regime, scale, and dominant-effect cues. Adjust the calculator below and compare the moving graphic with the computed result.

input scale

model

check

modified wavenumberdispersiondissipationfinite difference

formula

KaTeX rendered

\begin{aligned}\text{d phi/dx \~{}= i k* phi}\\[0.35em]\text{k* h = modified wavenumber}\end{aligned}

ASCII source

d phi/dx ~= i k* phi, k* h = modified wavenumber

schemek h

modified real

0.93204

phase ratio

0.77670

damping imag

0.63764

points/wave

5.24

Modified-wavenumber plots show why under-resolved waves travel at the wrong speed or get damped by upwind bias.

modified wavenumber dispersion dissipation finite difference