Seminar 10th July 2014 10:15 a.m. Seminar Room: B176/Rm2013 at Boldrewood campus
Airflow distortion over merchant ships: problems and solutions
Dr.Ben Moat
Marine Physics and Ocean Climate Group, National Oceanography Centre, Southampton.
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- https://noc.ac.uk/people/bim
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- CFD
- Submitter
- Luke Goater
Dr Ben Moat
Abstract:
Wind speed measurements obtained from ship-mounted anemometers are biased by the presence of the ship distorting the flow of air to the anemometer. Quantifying this bias is important in order to obtain the accurate wind speed measurements needed for ocean–atmosphere model forcing, coupled ocean–atmosphere model validation, satellite validation, and to quantify and predict possible changes in climate. We have used CFD models to simulate the flow around very detailed representations of individual research ships in order to quantify the effects of flow distortion at the anemometer locations. Such anemometers are generally in well-exposed positions, typically on a mast in the bows of the ship. In contrast, very little is known about the possible effects of airflow distortion on the wind speed measurements from fixed anemometers on typical merchant ships. This is because (1) the several thousand or so merchant vessels vary significantly in shape and size and it would be impractical to study each individual ship, and (2) the anemometer location is not usually known.
The effects of flow distortion on anemometers located on research ships are found to vary only slightly with variations in wind speed, but are very sensitive to the relative wind direction and, if uncorrected, can cause large biases in ship-based meteorological measurements. The influence of distortion on the flow above the bridges of 'typical' merchant ships is shown to be significant, with possible biases in the measured wind speed of between +11% and -100%, depending on the anemometer location.
Biography
Ben Moat completed his PhD from the department of Ship Science, University of Southampton in 2003 (Supervised by Prof. Tony Molland). He is working at the National Oceanography Centre, Southampton and has interests in the North Atlantic Overturning circulation, deep ocean heat content, wave breaking and whitecaps, air-sea fluxes of heat and moisture in the Arctic and the correction of wind speed measurements for the distortion of the airflow by the ship. He was awarded the Denny medal in 2010 and is a Fellow of the Royal Meteorological Society.