A transparent three-zone horizontal Bridgman furnace was used for the crystal growth of sodium nitrate. During crystal growth, the heating profiles and the growth front shape as well as flow patterns were recorded. To further understand the heat flow, a three-dimensional computer model based on an efficient multigrid finite volume method was also used to simulate the growth. Key process parameters, including the heating profiles, the growth rate, and the booster heating, were considered and their effects on the interface shape and the flow structures were discussed. It was observed that both buoyancy and Marangoni flows were dominant in the melt causing a highly concave interface. As a result, single-crystal growth was very difficult, Suitable insulation at the furnace bottom reduced interface deflection. Further, interface inversion was obtained by using a booster healing while keeping a cold spot at the top furnace wall near the interface by blowing cooling air. The obtained convex interface shape thus made the growth of a single crystal much easier.