Basic Boundary Conditions

in OpenFOAM v2.4

Classification

Steady Time-

varying

Dirichlet

Neumann

Robin Not

Implemented

Periodic

Symmetry

fixedValue uniformFixedValue

fixedGradient uniformFixedGradient

zeroGradient

mixed

cyclic

𝜙 𝒙 = 𝑓 𝒙 𝜙 𝒙, 𝑡 = 𝑓 𝒙, 𝑡

𝜕𝜙

𝜕𝒏𝒙 = 𝑔 𝒙

𝜕𝜙

𝜕𝒏𝒙, 𝑡 = 𝑔 𝒙, 𝑡

𝜕𝜙

𝜕𝒏𝒙 = 0

a𝛼 𝒙 𝜙 𝒙

+𝛽 𝒙𝜕𝜙

𝜕𝒏𝒙 = ℎ 𝒙

cyclicAMI

mixed BC

mixed fixedValue

fixedGradient

=

+ ×

× w

(1-w)

w

fixedValue

fixedGradient

W = 1

W = 0

mixed

symmetryPlane

symmetryPlane or slip?

𝜕𝜙

𝜕𝒏𝒙 = 0

Scalar 𝜙 Vector 𝝓

𝝓 𝒙 ∙ 𝒏 = 0, 𝜕𝝓𝑡

𝜕𝒏𝒙 = 𝟎

symmetryPlane is used on

a single and perfectly flat boundary

slip can be used on curved boundaries

symmetryPlane slip

𝒏

mixed BC is a combination of

fixedValue and fixedGradient BCs

A weighting parameter w (0-1) switches between these types

directionMixed BC

For vector fields, directionMixed BC

is a combination of fixedValue and

fixedGradient BCs

A weighting parameter (tensor) controls which direction these BCs are apply to

1

2𝒏⊗ 𝒏 + 𝒏⊗𝒏 𝑇

w

𝑂3 (Zero matrix)

𝐼3 (Identity matrix) fixedValue

fixedGradient

fixedGradient

fixedValue

Normal direction

Tangential direction

All directions