Use the Monopole Point Source node to add a monopole point source in 3D components on any point and in 2D axisymmetric components on points on the axis of symmetry. This is a source that is uniform and equally strong in all directions. A monopole represents a radially pulsating sphere in the limit where the radius tends to zero. The monopole point source adds a point source term to the right-hand side of the governing Helmholtz equation such that:
where 
is the delta function in three dimensions and adds the source at the point where x = x0. The monopole amplitude
S (SI unit: N/m
2) depends on the source type selected, as discussed below.
Select Flow to add an monopole point source located at
x = x0 defined in terms of the volume flow rate out from source
QS and the phase
of the source. The source defines the following monopole amplitude:
Select Intensity to define the source in terms of the free space reference RMS intensity
Irms it radiates. In a homogeneous medium, the specified intensity is obtained (the reference), but with other objects and boundaries present the actual intensity is different. The source defines the following monopole amplitude:
where dsrc is the distance from the source where the intensity
Irms is specified and
is the phase of the source. Enter values or expressions for:
When Power is selected, specify the source’s reference RMS strength by stating the power it radiates. In a homogeneous medium, the specified power is obtained (the reference), but with other objects and boundaries present the actual power is different. The source defines the following monopole amplitude:
where Pref denotes the radiated RMS power per unit length measured in W/m. Enter values or expressions for:
