SLAB THERMAL RESISTANCE WITH CONSTRICTION This two-dimensional steady-state heat conduction calculator provides the total conduction thermal resistance (without convective resistance) through the height axis of a solid slab, flat heat pipe, or heat spreader, including the thermal constriction resistance resulting from a heat source that is smaller than the slab, given uniform heat input and output, and having all other surfaces insulated. Variable Unit Value Source Width m Source Length m Slab Width m Slab Length m Slab Height m Thermal Conductivity W/m·°K Film Coefficient (sink) W/m^2·°K       Thermal Resistance °C/W