Derivation of Morison's force coefficients by three alternative forms of the method of moments
Morison's equation is the most widely used method of predicting wave forces on slim cylindrical members of offshore structures. The equation assumes that the wave force is composed of two components: a drag force and an inertial force, where the drag component is due to water particle velocity...
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American Society of Mechanical Engineers (ASME)
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ftunivmalaysia:oai:generic.eprints.org:73642 2023-05-15T14:25:25+02:00 Derivation of Morison's force coefficients by three alternative forms of the method of moments Mohd. Zaki, N. I. Abu Husain, M. K. Najafian, G. 2016 http://eprints.utm.my/73642/ https://www.scopus.com/inward/record.uri?eid=2-s2.0-84996593387&doi=10.1115%2fOMAE2016-54201&partnerID=40&md5=499dc3c550bffbe6f7f1ef85106240ae unknown American Society of Mechanical Engineers (ASME) Mohd. Zaki, N. I. and Abu Husain, M. K. and Najafian, G. (2016) Derivation of Morison's force coefficients by three alternative forms of the method of moments. In: ASME 2016 35th International Conference on Ocean, Offshore and Arctic Engineering, OMAE 2016, 19-24 June 2016, Busan, South Korea. T Technology (General) Conference or Workshop Item PeerReviewed 2016 ftunivmalaysia 2017-12-05T15:57:26Z Morison's equation is the most widely used method of predicting wave forces on slim cylindrical members of offshore structures. The equation assumes that the wave force is composed of two components: a drag force and an inertial force, where the drag component is due to water particle velocity and the inertial component is due to water particle acceleration. Morison's equation has two empirical coefficients, which are usually referred to as the drag and inertia coefficients. The values of these empirical coefficients are determined from laboratory and/or field experiments. In a typical wave load investigation, the wave force together with corresponding water particle velocity and acceleration are measured. The measured data is then analysed to calculate constant values for drag and inertia coefficients. One of the methods used in derivation of these coefficients is the (conventional) method of moments. However, the coefficients obtained from this method show considerable scatter due to large sampling variability. The purpose of this paper is to compare the sampling variability of drag and inertia coefficients from the conventional method of moments with those derived from two alternative forms of the method, i.e. methods of linear and low-order moments. Simulated data has been used to compare the efficiency of the three methods of moments. The results indicate that in most cases, the method of linear moments is superior to the other two methods. This is particularly true for drag-dominated forces. Conference Object Arctic Universiti Teknologi Malaysia: Institutional Repository |
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Universiti Teknologi Malaysia: Institutional Repository |
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T Technology (General) Mohd. Zaki, N. I. Abu Husain, M. K. Najafian, G. Derivation of Morison's force coefficients by three alternative forms of the method of moments |
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T Technology (General) |
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Morison's equation is the most widely used method of predicting wave forces on slim cylindrical members of offshore structures. The equation assumes that the wave force is composed of two components: a drag force and an inertial force, where the drag component is due to water particle velocity and the inertial component is due to water particle acceleration. Morison's equation has two empirical coefficients, which are usually referred to as the drag and inertia coefficients. The values of these empirical coefficients are determined from laboratory and/or field experiments. In a typical wave load investigation, the wave force together with corresponding water particle velocity and acceleration are measured. The measured data is then analysed to calculate constant values for drag and inertia coefficients. One of the methods used in derivation of these coefficients is the (conventional) method of moments. However, the coefficients obtained from this method show considerable scatter due to large sampling variability. The purpose of this paper is to compare the sampling variability of drag and inertia coefficients from the conventional method of moments with those derived from two alternative forms of the method, i.e. methods of linear and low-order moments. Simulated data has been used to compare the efficiency of the three methods of moments. The results indicate that in most cases, the method of linear moments is superior to the other two methods. This is particularly true for drag-dominated forces. |
format |
Conference Object |
author |
Mohd. Zaki, N. I. Abu Husain, M. K. Najafian, G. |
author_facet |
Mohd. Zaki, N. I. Abu Husain, M. K. Najafian, G. |
author_sort |
Mohd. Zaki, N. I. |
title |
Derivation of Morison's force coefficients by three alternative forms of the method of moments |
title_short |
Derivation of Morison's force coefficients by three alternative forms of the method of moments |
title_full |
Derivation of Morison's force coefficients by three alternative forms of the method of moments |
title_fullStr |
Derivation of Morison's force coefficients by three alternative forms of the method of moments |
title_full_unstemmed |
Derivation of Morison's force coefficients by three alternative forms of the method of moments |
title_sort |
derivation of morison's force coefficients by three alternative forms of the method of moments |
publisher |
American Society of Mechanical Engineers (ASME) |
publishDate |
2016 |
url |
http://eprints.utm.my/73642/ https://www.scopus.com/inward/record.uri?eid=2-s2.0-84996593387&doi=10.1115%2fOMAE2016-54201&partnerID=40&md5=499dc3c550bffbe6f7f1ef85106240ae |
genre |
Arctic |
genre_facet |
Arctic |
op_relation |
Mohd. Zaki, N. I. and Abu Husain, M. K. and Najafian, G. (2016) Derivation of Morison's force coefficients by three alternative forms of the method of moments. In: ASME 2016 35th International Conference on Ocean, Offshore and Arctic Engineering, OMAE 2016, 19-24 June 2016, Busan, South Korea. |
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1766297821440376832 |