Wave energy conversion is an active field of research, aiming to harness the vast amounts of energy present in ocean waves. An essential development trajectory towards an economically competitive wave energy converter (WEC) requires early device experimentation and refinement using numerical tools. OpenFOAM ® is proving to be a useful numerical tool for WEC development, having been increasingly employed in recent years to simulate and analyse the performance of WECs. This chapter reviews the latest works employing OpenFOAM ® in the field of wave energy conversion, and then presents the new application, of evaluating energy maximising control systems (EMCSs) for WECs, in an OpenFOAM ® numerical wave tank (NWT). The advantages of using OpenFOAM ® for this application are discussed, and implementation details for simulating a controlled WEC in an OpenFOAM ® NWT are outlined. An illustrative example is given, and results are presented, highlighting the value of evaluating EMCSs for WECs in an OpenFOAM ® NWT.