Ship squat prediction using a potential flow Rankine source method

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Authors
  1. McTaggart, K.
Corporate Authors
Defence Research and Development Canada, Atlantic Research Centre, Halifax NS (CAN)
Abstract
A numerical method has been developed predicting ship squat, with the goal of providing guidance to ship operators for avoidance of grounding in shallow water. The method assumes potential flow, and computations are sufficiently fast to allow evaluation for large numbers of conditions within practical time scales. Boundary conditions on the hull, free surface, and canal walls are satisfied using planar Rankine sources on solid boundaries and point Rankine sources placed a nominal distance above the calm waterline or free surface. Four different models of the free surface boundary condition have been implemented, ranging from a nominally at free surface to fully nonlinear. For ships with a transom stern, the influence of flow separation is modelled using a virtual stern, which extends aftward from the transom to a location with zero width. The numerical method is generally robust, except for in the vicinity of critical flow conditions. Validation with model tests has been used to develop an envelope for over-prediction of bottom clearance, which can be considered when developing guidance for ship operators.
Keywords
Heave;pitch;potential flow;ship;squat;trim
Report Number
DRDC-RDDC-2017-P105 — External Literature
Date of publication
06 Feb 2018
Number of Pages
33
DSTKIM No
CA045535
CANDIS No
805956
Format(s):
Electronic Document(PDF)

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