The thermally developing laminar forced-convection flow and heat transfer characteristics in corrugated ducts confined by sinusoidal and arc curves, which are often encountered in honeycomb desiccant wheels, are numerically investigated via the boundary-fitted coordinate system. The control volume-based finite difference technique is applied to obtain the solution utilizing the numerically generated boundary-fitted coordinates. According to this method, the complex domain in the physical plane is transformed into a regular square domain in the computational plane. Studied and graphically illustrated are the effects of aspect ratios and bending ratios of the ducts on the friction coefficients and heat transfer coefficients under uniform wall temperature (T) boundary conditions. For the special cases of corrugated ducts such as circular, square, and flat sinusoidal, the results are compared with some findings in the literature, and very good agreement is obtained. Furthermore, variations of the bulk temperature, Nusselt numbers, velocity, and temperature profiles in the entire thermal entry region are plotted.