{"title":"斜底破碎波涡动黏度的实验研究及与经验和数值预测的比较","authors":"N. Oldekop, T. Liiv, J. Laanearu","doi":"10.3176/PROC.2019.3.07","DOIUrl":null,"url":null,"abstract":"Focus is on the turbulence for a plunging breaker. Laser Doppler anemometer point measurements were used to determine the velocity matrix of a breaking wave on a sloping bottom. Using the Reynolds stress anisotropy for incompressible fluid, it was found that the ensemble averaged measured velocity predicted eddy viscosity is associated with peaks, which are absent in the broadly accepted empirical predictions. The instantaneous eddy viscosity coefficient was determined according to the Reynolds stresses, modified mean velocity and its gradient components and turbulent kinetic energy. The modified mean velocity and its derivatives improve eddy viscosity predictions during the wave period, which gives evidence that the velocity used corresponds well to a rotational part. In addition to the measurement predictions, empirical formulae were used to estimate the eddy viscosity values during the wave period. Furthermore, a meshless numerical model is proposed to determine artificial viscosity and demonstrate its dependence on eddy viscosity in the case of weakly compressible fluid.","PeriodicalId":54577,"journal":{"name":"Proceedings of the Estonian Academy of Sciences","volume":null,"pages":null},"PeriodicalIF":1.0000,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Experimental study of eddy viscosity for breaking waves on sloping bottom and comparisons with empirical and numerical predictions\",\"authors\":\"N. Oldekop, T. Liiv, J. Laanearu\",\"doi\":\"10.3176/PROC.2019.3.07\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"Focus is on the turbulence for a plunging breaker. Laser Doppler anemometer point measurements were used to determine the velocity matrix of a breaking wave on a sloping bottom. Using the Reynolds stress anisotropy for incompressible fluid, it was found that the ensemble averaged measured velocity predicted eddy viscosity is associated with peaks, which are absent in the broadly accepted empirical predictions. The instantaneous eddy viscosity coefficient was determined according to the Reynolds stresses, modified mean velocity and its gradient components and turbulent kinetic energy. The modified mean velocity and its derivatives improve eddy viscosity predictions during the wave period, which gives evidence that the velocity used corresponds well to a rotational part. In addition to the measurement predictions, empirical formulae were used to estimate the eddy viscosity values during the wave period. Furthermore, a meshless numerical model is proposed to determine artificial viscosity and demonstrate its dependence on eddy viscosity in the case of weakly compressible fluid.\",\"PeriodicalId\":54577,\"journal\":{\"name\":\"Proceedings of the Estonian Academy of Sciences\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":1.0000,\"publicationDate\":\"2019-01-01\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Proceedings of the Estonian Academy of Sciences\",\"FirstCategoryId\":\"103\",\"ListUrlMain\":\"https://doi.org/10.3176/PROC.2019.3.07\",\"RegionNum\":4,\"RegionCategory\":\"综合性期刊\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q3\",\"JCRName\":\"MULTIDISCIPLINARY SCIENCES\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Proceedings of the Estonian Academy of Sciences","FirstCategoryId":"103","ListUrlMain":"https://doi.org/10.3176/PROC.2019.3.07","RegionNum":4,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"MULTIDISCIPLINARY SCIENCES","Score":null,"Total":0}
Experimental study of eddy viscosity for breaking waves on sloping bottom and comparisons with empirical and numerical predictions
Focus is on the turbulence for a plunging breaker. Laser Doppler anemometer point measurements were used to determine the velocity matrix of a breaking wave on a sloping bottom. Using the Reynolds stress anisotropy for incompressible fluid, it was found that the ensemble averaged measured velocity predicted eddy viscosity is associated with peaks, which are absent in the broadly accepted empirical predictions. The instantaneous eddy viscosity coefficient was determined according to the Reynolds stresses, modified mean velocity and its gradient components and turbulent kinetic energy. The modified mean velocity and its derivatives improve eddy viscosity predictions during the wave period, which gives evidence that the velocity used corresponds well to a rotational part. In addition to the measurement predictions, empirical formulae were used to estimate the eddy viscosity values during the wave period. Furthermore, a meshless numerical model is proposed to determine artificial viscosity and demonstrate its dependence on eddy viscosity in the case of weakly compressible fluid.
期刊介绍:
The Proceedings of the Estonian Academy of Sciences is an international scientific open access journal published by the Estonian Academy of Sciences in collaboration with the University of Tartu, Tallinn University of Technology, Tallinn University, and the Estonian University of Life Sciences.
The journal publishes primary research and review papers in the English language. All articles are provided with short Estonian summaries.
All papers to be published in the journal are peer reviewed internationally.
The journal is open to word-wide scientific community for publications in all fields of science represented at the Estonian Academy of Sciences and having certain connection with our part of the world, North Europe and the Baltic area in particular.