Current work aims to study the geometry of an overtopping wave energy converter in real scale using Constructal Design. Problem studied here is submitted to two constraints (areas of wave tank and overtopping ramp) and two degrees of freedom: ratio between the height and length of ramp (H-1/L-1) (or ramp slope, (3) and distance between the bottom of wave tank and the device (S). The effect of H-1/L-1 and S over dimensionless device available power (P-d) is evaluated for three different ramp area fractions (0) and two different monochromatic waves. Conservation equations of mass, momentum and one equation for the transport of water volume fraction are solved with the finite volume method. To tackle with water-air mixture, multiphase model Volume of Fluid is used. Results showed the applicability of Constructal Design for improvement of device performance. For fixed magnitudes of S, the highest magnitudes of P-d are achieved for the lowest possible ratio of H-1/L-1. For smaller construction areas of the ramp, intermediate magnitudes of S led to the highest magnitudes of P-d, i.e., the sinking of device does not led necessarily to the best performance. Moreover, optimal shapes are not universal (the same) for the two wave conditions studied. (C) 2017 Elsevier Ltd. All rights reserved.