Browser-based CFD and fluid mechanics calculators. No login, no install — enter your values and get results instantly. For educational use.
Estimate the required first cell height to achieve a target y+ value. Uses flat-plate boundary layer correlations. Defaults: air at 10 m/s over a 1 m plate.
Re_L = ρ·U·L / μ
Cf = 0.026·Re_L^(-1/7) [turbulent flat plate]
τ_w = Cf · ½ρU²
u* = √(τ_w / ρ)
Δy = y+ · μ / (ρ · u*)
Calculate Reynolds number for pipe flow, flat plate, and channel flow with automatic regime classification. Defaults: air at 10 m/s in a 0.1 m pipe.
Re = ρ·U·L / μ = U·L / ν
Laminar: Re < 2300 (pipe)
Transition: 2300 ≤ Re < 4000
Turbulent: Re ≥ 4000
Compute k, ε, ω, and νt from freestream turbulence intensity and length scale. Use these values as inlet boundary conditions in ANSYS Fluent or OpenFOAM. Defaults: 10 m/s, 5% intensity.
k = 1.5·(U·I)²
ε = Cμ^(3/4) · k^(3/2) / l
ω = k^(1/2) / (Cμ^(1/4) · l)
νt = Cμ · k² / ε
Calculate Mach number, stagnation temperature and pressure, and dynamic pressure. Identify the flow regime. Defaults: air at 300 K, 200 m/s.
a = √(γRT)
Ma = U / a
T₀ = T·(1 + (γ-1)/2·Ma²)
P₀ = P·(T₀/T)^(γ/(γ-1))
q = ½·γ·P·Ma²
Calculate the terminal settling velocity of a spherical particle falling under gravity in a viscous fluid. Uses iterative Stokes / transitional / Newton drag correlations. Defaults: 100 μm sand in water.
Stokes (Re<0.1): Cd = 24/Re
Transitional: Cd = 24/Re + 6/(1+√Re) + 0.4
Newton (Re>1000): Cd ≈ 0.44
vt from: ¾·Cd·(ρf/ρp)·(vt²/gd) = (ρp-ρf)/ρp
Estimate the Courant–Friedrichs–Lewy number for your mesh and time step, with stability guidance for explicit and implicit solvers. Defaults: air at 10 m/s, 1 mm cell, 1e-4 s time step.
CFL = U · Δt / Δx
Explicit schemes: CFL ≤ 1 for stability
Implicit schemes: CFL > 1 allowed (accuracy ↓)
Recommended: CFL ≈ 0.5 for explicit