A standard and a VOF tracer are advected by an axisymmetric flow. The initial interface is a torus which is then advected by the flow illustrated in Figure 76. As the torus is flattened against the right-hand-side wall, its cross-sectional surface area decreases but the volume should remain constant. This is indeed the case to within 0.04% for the VOF tracer and 1.5× 10−5% for the standard tracer.
A similar test but for tracers advected around a solid sphere.