This paper presents an efficient and versatile OpenFOAM(Open-source Field Operation And Manipulation)-based numerical solver for fully resolved simulations that can handle any rigid and deforming bodies moving in the ...This paper presents an efficient and versatile OpenFOAM(Open-source Field Operation And Manipulation)-based numerical solver for fully resolved simulations that can handle any rigid and deforming bodies moving in the fluid.The algorithm used for solving Fluid-Structure Interactions(FSI)involving the immersed structure with changeable shapes is based on the momentum redistribution method.The present approach excludes the need to solve elastic equations,obtain high-accuracy predictions of the flow field and provide a rigorous basis for implementing the Immersed Boundary Method(IBM).The OpenFOAM implementation of the algorithm is discussed along with the design methodology for developing bio-inspired underwater vehicles using the present solver.The computational results are validated with the experimental observations of the two-dimensional and three-dimensional anguilliform swimmer case studies.The study further extended to the three-dimensional hydrodynamics of a bioinspired,self-propelling manta bot.The motion of the body is specified a priori according to the reported experimental observations.The results quantify the vortex formation and shedding processes and enable the identification of the portions of the body responsible for the majority of thrust.The body accelerates from rest to an asymptotic mean forward velocity of 0.2 ms^(-1)in almost 5 s,consistent with experimental observations.It is observed that the developed computational model is capable of performing any motion simulation and manoeuvrability analysis,which are critical for the designers to develop novel unmanned underwater vehicles.展开更多
North China is a key region for studying geophysical progress. In this study, ground-based and Gravity Recovery and Climate Experiment（GRACE） gravity data from 2009 to 2013 are used to calculate the gravity change r...North China is a key region for studying geophysical progress. In this study, ground-based and Gravity Recovery and Climate Experiment（GRACE） gravity data from 2009 to 2013 are used to calculate the gravity change rate（GCR） using the polynomial fitting method. In general, the study area was divided into the Shanxi rift, Jing-Jin-Ji（Beijing-Tianjin-Hebei Province）, and Bohai Bay Basin（BBB） regions. Results of the distribution of the GCR determined from ground-based gravimetry show that the GCR appears to be ＂negativepositive-negative＂ from west to east, which indicates that different geophysical mechanisms are involved in the tectonic activities of these regions. However, GRACE solutions are conducted over a larger spatial scale and are able to show a difference between southern and northern areas and a mass redistribution of land water storage.展开更多
基金the funding received from Naval Research Board,Marine System Panel to carry out this research work at Shiv Nadar University.Award Number:NRB/4003/PG/400,Recipient:Dr.Santanu Mitra,Ph.D.,Assoc.Professor,Mechanical Engineering Department,Shiv Nadar University.
文摘This paper presents an efficient and versatile OpenFOAM(Open-source Field Operation And Manipulation)-based numerical solver for fully resolved simulations that can handle any rigid and deforming bodies moving in the fluid.The algorithm used for solving Fluid-Structure Interactions(FSI)involving the immersed structure with changeable shapes is based on the momentum redistribution method.The present approach excludes the need to solve elastic equations,obtain high-accuracy predictions of the flow field and provide a rigorous basis for implementing the Immersed Boundary Method(IBM).The OpenFOAM implementation of the algorithm is discussed along with the design methodology for developing bio-inspired underwater vehicles using the present solver.The computational results are validated with the experimental observations of the two-dimensional and three-dimensional anguilliform swimmer case studies.The study further extended to the three-dimensional hydrodynamics of a bioinspired,self-propelling manta bot.The motion of the body is specified a priori according to the reported experimental observations.The results quantify the vortex formation and shedding processes and enable the identification of the portions of the body responsible for the majority of thrust.The body accelerates from rest to an asymptotic mean forward velocity of 0.2 ms^(-1)in almost 5 s,consistent with experimental observations.It is observed that the developed computational model is capable of performing any motion simulation and manoeuvrability analysis,which are critical for the designers to develop novel unmanned underwater vehicles.
基金supported by the National Natural Science Foundation of China(41304060)the national key basic research and development plan(2013CB733304)
文摘North China is a key region for studying geophysical progress. In this study, ground-based and Gravity Recovery and Climate Experiment（GRACE） gravity data from 2009 to 2013 are used to calculate the gravity change rate（GCR） using the polynomial fitting method. In general, the study area was divided into the Shanxi rift, Jing-Jin-Ji（Beijing-Tianjin-Hebei Province）, and Bohai Bay Basin（BBB） regions. Results of the distribution of the GCR determined from ground-based gravimetry show that the GCR appears to be ＂negativepositive-negative＂ from west to east, which indicates that different geophysical mechanisms are involved in the tectonic activities of these regions. However, GRACE solutions are conducted over a larger spatial scale and are able to show a difference between southern and northern areas and a mass redistribution of land water storage.
