Frostbite occurs when body tissues freeze after being exposed to extreme cold and wind. It?s most likely to occur on body extremities ? fingers, nose, ears, and toes ? areas far from the warm body core and exposed to the elements. We have modeled tissue freezing in a finger in order to predict combinations of wind speed and temperature likely to lead to frostbite. Our model incorporates different tissue layers in the finger, sources of heat, transient properties, and heat transfer through convection and conduction. Such a model is valuable because it accurately predicts the existence and extent of tissue freezing.

The model uses two tissue layers in the finger because of their disparaging material properties. It also contains a region attached to the finger to simulate heat flux from the hand to the finger. Heat generation was ignored, and heat transfer to the finger from blood flow was accounted for by a source term. The model is axi-symmetric, with radial heat flow into the finger. The edges of the finger have a convection boundary condition, and the region attached to the finger was perfectly insulated. The far edge of the region attached to the finger was set to a constant temperature equal to average body temperature.

Each simulation was performed for a time span of thirty minutes for each set of ambient conditions. We then noted whether or not the conditions were conducive to frostbite. A sensitivity analysis was performed to ensure that the solutions converged.