Vasomotricity

These two global controlled variables are calculated separately by the controller and are used for the calculation of the local controlled variables of the elements:

For the vasomotricity, the local controlled variable is given by the variation of the volumetric blood flux ${\dot{V}}_{BLOOD}$ that flows through the various skin parts. The local effect of the skin temperatures of the segments is taken into account when the volumetric blood fluxes in the skin parts are calculated.

A decrease in skin temperature of 10 °C leads to an increase of resistance in the blood vessels [10]. This effect is taken into account through the factor $2^{({\theta }_{4,j}/6)}$. The volumetric blood flux through the skin parts is composed as follows:

The above equation connects the local and the global controlled variables. The global controller constants are:

The vasoconstriction shows a high sensitivity with respect to the head core temperature and the skin temperature. For the calculation of the vasoconstriction controlled variable signal, a multiplicative approach is chosen. The controller constant is in this case:

The influence of vasodilation on the skin elements is investigated in [6]. Based on those results, the distribution for the vasodilation is chosen from the values that return the biggest dilation of the blood vessels.

The local constants for vasodilation and vasoconstriction are listed in the following table: