A typical Snowman holding a shovel was modelled using Computational Fluid Dynamics (CFD) methods. The geometry was created using Boolean geometry. Meshing of the Snowman surface used triangular facets, with a tetrahedral volume mesh. Away from the Snowman surface, a hexahedral volume mesh was used. Local mesh refinement was made around the Snowman details like eyes, buttons and arms. The initial mesh size was approximately 300,000 volume elements, and took approximately 3 hours to construct from initial concept to initial CFD simulation.

A cross wind of 0.3m/s was simulated, using a standard k-ε turbulence model, with second order upwind numerical resolution, and standard wall functions. Carbon monoxide and ash particulates emanating from the corn cob pipe were included in the simulations. The species and Discrete Phase Models (DPM), with stochastic turbulent particle tracking, were used to calculate the CO plume and ash paths respectively.

Local mesh refinement was undertaken after initial simulation to resolve the flow field for complex section of the mesh, especially around the corn cob pipe. The final mesh size was approximately 700,000 tetrahedral and hexahedral volume elements.

Pathlines were seen to travel around the Snowman’s large belly, and downwards from his hat, producing a complex three dimensional wake. Evidence of minor transient vortex shedding was observed in the steady state solution. With a Reynolds Number in excess of 2x10⁴ – based on Snowman waist – some vortex shedding is expected.

Analysis of the air velocity around the Snowman indicated that the heat transfer, and hence melting, from its belly and back is greatest under the current cross wind conditions. A mixture of forced and natural convection leads to an average heat transfer coefficient of approximately 2 W/m².K.

The discharge of carbon monoxide and ash from the corn cob pipe indicated that the gaseous plume and particulate matter travel differently. The larger ash particles tend towards the ground under the influence of gravity, while the carbon monoxide plume is significantly influenced by thermal buoyancy.