Highly Accurate Experimental Heave Decay Tests with a Floating Sphere: A Public Benchmark Dataset for Model Validation of Fluid-Structure Interaction
Journal article, 2021

Highly accurate and precise heave decay tests on a sphere with a diameter of 300 mm were completed in a meticulously designed test setup in the wave basin in the Ocean and Coastal Engineering Laboratory at Aalborg University, Denmark. The tests were dedicated to providing a rigorous benchmark dataset for numerical model validation. The sphere was ballasted to half submergence, thereby floating with the waterline at the equator when at rest in calm water. Heave decay tests were conducted, wherein the sphere was held stationary and dropped from three drop heights: a small drop height, which can be considered a linear case, a moderately nonlinear case, and a highly nonlinear case with a drop height from a position where the whole sphere was initially above the water. The precision of the heave decay time series was calculated from random and systematic standard uncertainties. At a 95% confidence level, uncertainties were found to be very low-on average only about 0.3% of the respective drop heights. Physical parameters of the test setup and associated uncertainties were quantified. A test case was formulated that closely represents the physical tests, enabling the reader to do his/her own numerical tests. The paper includes a comparison of the physical test results to the results from several independent numerical models based on linear potential flow, fully nonlinear potential flow, and the Reynolds-averaged Navier-Stokes (RANS) equations. A high correlation between physical and numerical test results is shown. The physical test results are very suitable for numerical model validation and are public as a benchmark dataset.


fully nonlinear potential flow


linear potential flow

structure interaction

heave decay

physical tests



benchmark dataset

wave energy converters


Morten Bech Kramer

Aalborg University

Floating Power Plant

Jacob Andersen

Aalborg University

Sarah Thomas

Floating Power Plant

Flemming Buus Bendixen


Harry Bingham

Technical University of Denmark (DTU)

Robert Read

Technical University of Denmark (DTU)

Nikolaj Holk

Aalborg University

Edward Ransley

University of Plymouth

Scott Brown

University of Plymouth

Yi-Hsiang Yu

National Renewable Energy Laboratory

Thanh Toan Tran

National Renewable Energy Laboratory

Josh Davidson

Budapest University of Technology and Economics

Csaba Horvath

Budapest University of Technology and Economics

Carl-Erik Janson

Chalmers, Mechanics and Maritime Sciences (M2), Marine Technology

Kim Nielsen

Aalborg University

Ramböll AB

Claes Eskilsson

Aalborg University

RISE Research Institutes of Sweden


1996-1073 (ISSN) 19961073 (eISSN)

Vol. 14 2 269

Subject Categories

Applied Mechanics

Geotechnical Engineering

Fluid Mechanics and Acoustics



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