Divergence · ∇ · F
F(x,y)—
Probe(1.00, 0.50)
derivation at probe
P =
Q =
∂P/∂x—
∂Q/∂y—
∇·F = ∂P/∂x + ∂Q/∂y—
Divergence theorem (locally): the fractional rate at which a
small blob's area changes equals ∇·F.
What this means: if F is fluid velocity, ∇·F > 0 marks a
source (mass appears), < 0 a sink (mass disappears),
= 0 means incompressible flow.
Drag the probe to explore.
red = positive (source / outflow)
blue = negative (sink / inflow)
gray = zero (incompressible)
drag orange dot · press ▶ play to run blob