A flexible network generation package for use in modeling and thermal analysis of tissue vasculature has been developed. This package can be used to simulate a wide variety of vascular networks with the long range goal being to simulate any tissue in the body. This modular package consists of four programs that are used interactively to generate network models. The first program (Unit Cell) creates individual vascular network “unit cells” of a user specified vascular anatomy distributed throughout a specified unit cell parallelpiped. The second program (Pack) then “packs” any three-dimensional space with these unit cell parallelpipeds (UCP’s) in a user specified manner. The third program (Connect) then connects the vessels of the various unit cell parallelpipeds that have been packed into the tissue. Finally, the fourth program (Flow Rates) assigns blood flow rates to each vessel. The network generation package produces files which are compatible with a hybrid finite-element / finite-difference based program which automatically generates finite-element meshes and computes the complete temperature fields. The network generation package allows the operator to create highly detailed, continuous vessel networks in a short amount of time.