# Main ContribExamples/OscillatingFixedValue

Searching the tutorials I couldn't find an example of how to use this type of boundary condition, so I've created a very small and simple tutorial. Basically, the setup requires the definition of 4 parameters:

   inlet
{
type oscillatingFixedValue;
amplitude       0.5;
frequency       0.2;
refValue        uniform (1 0 0);
}


The above setup enables to specify a velocity boundary condition for an entire patch that varies in time as:

   $1+amplitude\cdot\sin\left(2\pi\cdot frequency\cdot t\right)$


Sample OpenFOAM case - it applies to Valid versions:

Update - it applies to Valid versions:

As from OpenFOAM 2.1.x, the dictionary for this boundary condition should read as

   myPatch
{
type          oscillatingFixedValue;
value         uniform 0;    // Initialization value
refValue      uniform refV;    // Reference value for oscillation
offset        offset;           // Oscillation mean value offset
amplitude      constant Amp; // Amplitude of oscillation
frequency      constant freq; // frequency
}


for a given scalar field. If applied to vector field, value, offset and refValue should be modified accordingly. This dictionary specifies an oscillating boundary condition of a given scalar, for an entire patch, as:

   $\textrm{\textit{refV}} \cdot \left( 1.0 + \textrm{\textit{Amp}} \cdot \sin \left(2\pi\cdot \textrm{\textit{freq}}\cdot t\right)\right) + \textrm{\textit{offset}}$