The mesh in the upstream region of this case has been refined back to its original density. This restores the wave propagation behaviour through this region.
Reference: Duisburg Test Case (DTC) el Moctar, O., Shigunov, V., Zorn, T., Duisburg Test Case: Post-Panamax Container Ship for Benchmarking, Journal of Ship Technology Research, Vol.59, No.3, pp. 50-65, 2012