In the dry environments of high-temperature gas reactors, aerosols and dust particles can be highly nonspherical and even chainlike agglomerates, and are highly charged. To elucidate the role of both shape and charge on particle dynamics, we have explored numerical solutions of the Poisson equation for arbitrary geometries. In this paper, we describe the general computational framework, and report results for condensation/evaporation for several different cases, including chainlike agglomerates. We find that the shape factor based on the volume equivalent sphere approximation underestimates the actual condensation rate on the agglomerate, in addition to not accounting for the local condensation rates.