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Experimental investigations on the strategies of fighting crickets Velarifictorus micado to manipulate air resistance

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Science China(Physics,Mechanics & Astronomy) 2020年第6期63卷 54-65页

作者： Yun Xing JiaLing Yang Institute of Solid Mechanics Beihang UniversityBeijing 100191China

Fighting crickets,one species of flightless insects optimally chosen by nature for millions of years,have evolved to fairly smooth and streamlined body *** article tries to answer the question how the insects manipulate air resistance when travelling through air after take-off without using their wings and meanwhile keep a high *** found that fighting crickets,Velarifictorus micado,performed two types of movements through air:stable and *** two types both have a high moving *** the stable type,the moving efficiency is larger than 95%.As a typical example,focusing on the stable type,we firstly predicted each component of aerodynamic drag applied on the crickets and analysed the drag contributions to the initial kinetic energy *** investigation revealed the mechanisms of the efficiently moving strategy against air resistance for the *** results show that the crickets can spin their hind legs to adjust body posture,thereby changing(increasing or decreasing)the air drag acting on the body to raise the efficiency during aerial *** work may advance the understanding of the significance of hind legs to insects’evolution and provide inspiration for future robot or micro aerial vehicle designs.

关键词： aerial movement air resistance robot designs energy dissipation

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resistance of large caisson in floating transport considering the influence of air

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Frontiers of Structural and Civil Engineering 2010年第3期4卷 331-338页

作者： Junjie ZHENG Zongzhe LI Dongan ZHAO Qiang MA Rongjun ZHANG School of Civil Engineering and Mechanics Huazhong University of Science and TechnologyWuhan 430074China

This paper deals with the floating resistance of super large caisson by numerical simulation,and the influence of air resistance on the caisson,which is often ignored by previous researchers,is *** floating caisson of Taizhou Highway Bridge’s middle tower pier is investigated,and the software package FLUENT is used to simulate the floating process of largescale rounded rectangular steel *** simulation adopts the volume of fluid(VOF)model with water-air two-phase flow,which can take both the hydraulic resistance and air resistance into ***,the analyses on hydraulic resistance and air resistance under different working conditions,such as different flow velocities and different draughts of water are performed,and the results are compared with those calculated by related empirical *** comparison shows that the air resistance takes up notable portion in the total resistance on the floating caisson,and the effect of air resistance on the safety of caisson should be paid sufficient attention to rather than be ignored.

关键词： large-scale caisson numerical simulation hydraulic resistance air resistance

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Computational Solution to the Problems of Projectile Motion under Significant Linear Drag Effect

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Open Journal of Applied Sciences 2023年第4期13卷 508-528页

作者： Annasi Ayubu Said Msafiri Mmasa Mshewa Grant Charles Mwakipunda Mbega Ramadhani Ngata Elfakiri Ali Mohamed Department of Physics School of Mathematics and Physics China University of Geosciences Wuhan China Department of Physics Faculty of Natural Science Abdulrahman Al-Sumait University (Sumait-University) Zanzibar Tanzania Key Laboratory of Tectonics and Petroleum Resources Ministry of Education China University of Geosciences Wuhan China Department of Economic Zanzibar University Zanzibar Tanzania

This paper investigates the computational solution to the problem of projectile motion under a significant linear drag effect. The drag force acting on the particle within the medium of propagation is proportional to the cross-section area of the projectile, the velocity of the particle, and the medium’s density. From zero air resistance force (vacuum) the problems are well known with solutions, but with air resistance (drag force) the problems have no exact analytical solutions which lead to most of the significant scientific research works using numerical methods. Therefore, this study aims to present the analysis of the computational modelling of drag force exerted by the surrounding medium on the linear motion. However, the horizontal and vertical components of differential equations of motion were derived and characterized from the solutions governed by Newton’s 2nd law of motion. The baseball features were presented as the projectile (object) in this work. In addition, the numerical computational results were received from FreeMat. The results were discussed and compared with those from the vacuum. Moreover, the displacements, velocities, range, and trajectories of the projectile were all discussed and a conclusion was made.

关键词： Drag Force air resistance Projectile Newton’s Law

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Method of branch ariflow for calculatinga complicated mine ventilation networks

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Journal of Coal Science & Engineering(China) 2001年第1期7卷 64-69页

作者：刘泽功 University of Science and Technology of China

The solutions widely used at present for calculating complicated mine ventilation networks are ones in which resistance of the branches and characteristic parameters of the fans are taken as basic input data. But it is time and energy consuming to obtain the branch resistance values. A new solution is developed in this paper in which the branch resistance values are obtained through measuring and evaluating the airflow of the whole ventilation network. Theoretical analysis is made of the establishment of a linear equation series with branch resistance as unknown numbers, an equation series for which one, and only one, result of solutions exists. This solution is programmed in C language and passed on a personal computer. The programmed solution programmed proves of practical use, as demonstrated by specific examples. Being different from other solutions, the method takes the branch airflow and fan working points as basic input data, and the present solution is of greater advantage for calculating ventilation networks of mines in operation.

关键词： air resistance measurements calculation computers

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