Effect of Air Fraction on Force Coefficients in Oscillatory Flow

Malene Hovgaard Vested, Erik Damgaard Christensen

Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearchpeer-review

Abstract

The forces on marine and offshore structures are often affected by spilling breakers. The spilling breaker is characterized by a roller of mixed air and water with a forward speed approximately equal to the wave celerity. This high speed in the top of the wave has the potential to induce high wave loads on upper parts of the structures. This study analyzed the effect of the air content on the forces. The analyses used the Morison equation to examine the effect of the percentage of air on the forces. An experimental set-up was developed to include the injection of air into an otherwise calm water body. The air-injection did introduce a high level a turbulence. It was possible to assess the amount of air content in the water for different amounts of air-injection. In the mixture of air and water the force on an oscillating square cylinder was measured for different levels of air-content, - also in the case without air. The measurements indicated that force coefficients for clear water could be use in the Morison equation as long as the density for water was replaced by the density for the mixture of air and water.
Original languageEnglish
Title of host publicationProceedings of the ASME 2021 40th International Conference on Ocean, Offshore and Arctic Engineering
Number of pages8
Volume6: Ocean Engineering
PublisherAmerican Society of Mechanical Engineers
Publication date2021
Article numberV006T06A003
ISBN (Electronic)978-0-7918-8516-1
DOIs
Publication statusPublished - 2021
Event40th International Conference on Ocean, Offshore and Arctic Engineering (OMAE2021) - Virtual, Online event
Duration: 21 Jun 202130 Jun 2021

Conference

Conference40th International Conference on Ocean, Offshore and Arctic Engineering (OMAE2021)
LocationVirtual, Online event
Period21/06/202130/06/2021

Keywords

  • Wave loads
  • Air-entrainment
  • Force coefficients

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