Line Source on Axis
Use the Line Source on Axis node to add a line source on the axis of symmetry in 2D axisymmetric components. This type of source corresponds a radially vibrating cylinder in the limit where its radius tends to zero. The line source adds a source term to the right-hand side of the governing Helmholtz equation such that:
where δ(z − z0) is the delta function in 3D that adds the source on the axis of symmetry where z = z0 and r = 0, and dz is the line element along the z-axis (SI unit: m). The monopole amplitude S (SI unit: N/m2) depends on the source type selected and is the same as discussed in the 3D case for a Line Source.
For the Pressure Acoustics, Transient interface, only the Flow (no phase specification), User defined, and the Gaussian pulse source types are available. The Gaussian pulse source type has no effect in the frequency domain. See The Gaussian Pulse Source Type Settings.
Line Source on Axis
Select a Type: Flow (the default), Intensity, Power, or User defined. See the options and expression for Line Source. The sources are the same but in 2D axisymmetric components they are only applicable on the symmetry axis at r = 0.
Solution (datasets) in the COMSOL Multiphysics Reference Manual