We pursued a quantitative comparison of the continuum and mesoscale simulations of metal particle reactions in a condensed explosive. The continuum or homogeneous approximation assumed a single combustible mixture; contrastingly, in the present heterogeneous treatment of a mixture, aluminum and 1,3,5,7-tetranitro-1,3,5,7-tetrazocane were considered independent reactive granules of micron size with binder being inert material with strength. Both simulations similarly estimated the steady detonation velocity and peak pressure, while the early flame acceleration transients, marked by a complex flow structure behind the flame front, were observed only in the mesoscale simulation. The precise multi-interface processing techniques, combined with granule-level reactive flow models developed in this study, are deemed applicable to general heterogeneous solid fuel combustion studies related to granules of various size, shape, and reactivity. (C) 2020 The Author(s). Published by Elsevier Inc. on behalf of The Combustion Institute.