Simulations of plasma flow through a magnetic nozzle were conducted using the timedependent, three-dimensional magnetohydrodynamics code, MACH3. The code's grid generation and mesh adaptivity routines were upgraded to improve resolution of physical processes of varying characteristic scale. Modeling of simplified magnetic nozzle flow using constant and classical isotropic resistivity aims to verify and provide preliminary quantitative depiction of the core-plasma flow, evolution of the magnetic field, and conversion of stagnation enthalpy to directed exhaust thrust energy. For stagnation conditions of 100 eV and 0.355 MPa, steady-state modeling using helium propellant and constant resistivity demonstrates a nearly isentropic expansion through the nozzle to exhaust speeds near 160 km/s. As expected, simulations using classical resistivity also exhibit similar trends but deviate more from the ideal isentropic solution when compared to the simulations using constant resistivity. At fixed plasma pressure and applied field the exhaust velocity scaled appropriately as the square root of the stagnation temperature.