scholarly journals Bionic Nonsmooth Drag Reduction Mathematical Model Construction and Subsoiling Verification

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Baoguang Wu ◽  
Ruize Zhang ◽  
Pengfei Hou ◽  
Jin Tong ◽  
Deyi Zhou ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Drag Reduction ◽  
Field Experiments ◽  
Design Method ◽  
Reduction Rate ◽  
Movement Speed ◽  
Surface Drag ◽  
Movement Model ◽  
Surface Design ◽  
Pangolin Scale

In this study, a bionic nonsmooth drag-reducing surface design method was proposed; a mathematical model was developed to obtain the relationship between the altitude of the nonsmooth drag-reducing surface bulges and the spacing of two bulges, as well as the speed of movement, based on which two subsoiler shovel tips were designed and verified on field experiments. The mechanism of nonsmooth surface drag reduction in soil was analyzed, inspired by the efficient digging patterns of antlions. The nonsmooth surface morphology of the antlion was acquired by scanning electron microscopy, and a movement model of the nonsmooth surface in soil was developed, deriving that the altitude of the nonsmooth drag-reducing surface bulge is proportional to the square of the distance between two bulges and inversely proportional to the square of the movement speed. A flat subsoiler shovel tip and a curved tip were designed by applying this model, and the smooth subsoiler shovel tips and the pangolin scale bionic tips were used as controls, respectively. The effect of the model-designed subsoilers on drag reduction was verified by subsoiling experiments in the field. The results showed that the resistance of the model-designed curved subsoiler was the lowest, the resistance of the pangolin scale bionic subsoiler was moderate, and the resistance of the smooth surface subsoiler was the highest; the resistance of the curved subsoiler was less than the flat subsoilers; the resistance reduction rate of the model-designed curved subsoiler was 24.6% to 33.7% at different depths. The nonsmooth drag reduction model established in this study can be applied not only to the design of subsoilers but also to the design of nonsmooth drag reduction surfaces of other soil contacting parts.

Drag Reduction Study about Bird Feather Herringbone Riblets

2013 ◽  
Vol 461 ◽  
pp. 201-205 ◽  
Author(s):  
Hua Wei Chen ◽  
Fu Gang Rao ◽  
De Yuan Zhang ◽  
Xiao Peng Shang
Keyword(s):  
Drag Reduction ◽  
Structural Parameters ◽  
Reduction Rate ◽  
Reduction Mechanism ◽  
Surface Drag ◽  
Flight Feather ◽  
Hollow Shaft ◽  
Smooth Edge ◽  
Bird Feather ◽  
Wild Goose

Flying bird has gradually formed airworthy structures e.g. streamlined shape and hollow shaft of feather to improve flying performance by millions of years natural selection. As typical property of flight feather, herringbone-type riblets can be observed along the shaft of each feather, which caused by perfect alignment of barbs. Why bird feather have such herringbone-type riblets has not been extensively discussed until now. In this paper, microstructures of secondary feathers are investigated through SEM photo of various birds involving adult pigeons, wild goose and magpie. Their structural parameters of herringbone riblets of secondary flight feather are statistically obtained. Based on quantitative analysis of feathers structure, one novel biomimetic herringbone riblets with narrow smooth edge are proposed to reduce surface drag. In comparison with traditional microgroove riblets and other drag reduction structures, the drag reduction rate of the proposed biomimetic herringbone riblets is experimentally clarified up to 15%, much higher than others. Moreover, the drag reduction mechanism of herringbone riblets are also confirmed and exploited by CFD.

Effect of Bionic Concave Surface to the Drag Reduction Performance of Cylinder Sealing Ring

2014 ◽  
Vol 1055 ◽  
pp. 152-156 ◽  
Author(s):  
Gang Zhao ◽  
Fang Li ◽  
Wei Xin Liu ◽  
Jian Ying Zhao ◽  
Hong Shi Bi
Keyword(s):  
Drag Reduction ◽  
Reduction Rate ◽  
Cylinder Block ◽  
Lubricating Oil ◽  
Concave Surface ◽  
Movement Speed ◽  
Piston Velocity ◽  
Friction Resistance ◽  
Sealing Ring ◽  
Maximum Drag Reduction

According to the problem of large friction resistance exists between the sealing ring and the cylinder block when the piston cylinder works, the drag reduction technology of bionic concave surface was applied in the sealing ring. By building a drag reduction motion model of sealing ring with concave surface of triangular arrangement, the effect of drag reduction performance decided by concave diameter and piston velocity was studied with the method of numerical simulation. The results show that: when the piston velocity is fixed, the maximum drag reduction rate can be achieved with the concave diameter is 1.5mm, and the maximum drag reduction rate is 15.72%. Meanwhile when the diameter of the concave is fixed, the drag reduction rate increased gradually with the increase of initial speed, the drag reducing effect is best at the speed of 0.6m/s. In the process of piston movement, lubricating oil in concave shakes, and makes the lubricating oil flow to the inside wall of cylinder, which play the role of lubrication, so as to achieve the effect of reducing friction and increasing the movement speed of piston.

scholarly journals Investigation of the Turbulent Drag Reduction Mechanism of a Kind of Microstructure on Riblet Surface

Micromachines ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 59
Author(s):  
Mingrui Ao ◽  
Miaocao Wang ◽  
Fulong Zhu
Keyword(s):  
Drag Reduction ◽  
Three Dimensional ◽  
Reduction Rate ◽  
Water Area ◽  
Reduction Mechanism ◽  
Surface Drag ◽  
Groove Surface ◽  
Turbulent Drag ◽  
Micro Structures ◽  
Riblet Surface

With the k-ε renormalization group turbulence model, the drag reduction mechanism of three- dimensional spherical crown microstructure of different protruding heights distributing on the groove surface was studied in this paper. These spherical crown microstructures were divided into two categories according to the positive and negative of protruding height. The positive spherical crown micro-structures can destroy a large number of vortexes on the groove surface, which increases relative friction between water flow and the groove surface. With decreasing the vertical height of the spherical crown microstructure, the number of rupture vortexes gradually decreases. Due to the still water area causes by the blocking effect of the spherical crown microstructure, it was found that the shear stress on the groove surface can be reduced, which can form the entire drag reduction state. In another case, the spherical crown microstructures protrude in the negative direction, vortexes can be generated inside the spherical crown, it was found that these vortexes can effectively reduce the resistance in terms of pressure and friction. In a small volume, it was shown that the surface drag reduction rate of spherical crown microstructures protrudes in negative directions can be the same as high as 24.8%.

scholarly journals Nanofluid flow containing carbon nanotubes with quartic autocatalytic chemical reaction and Thompson and Troian slip at the boundary

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Muhammad Ramzan ◽  
Jae Dong Chung ◽  
Seifedine Kadry ◽  
Yu-Ming Chu ◽  
Muhammad Akhtar
Keyword(s):  
Mathematical Model ◽  
Carbon Nanotubes ◽  
Drag Force ◽  
Chemical Reaction ◽  
Slip Velocity ◽  
Volume Fraction ◽  
Surface Drag ◽  
Nanofluid Flow ◽  
Velocity Parameter ◽  
The Impact

Abstract A mathematical model is envisioned to discourse the impact of Thompson and Troian slip boundary in the carbon nanotubes suspended nanofluid flow near a stagnation point along an expanding/contracting surface. The water is considered as a base fluid and both types of carbon nanotubes i.e., single-wall (SWCNTs) and multi-wall (MWCNTs) are considered. The flow is taken in a Dacry-Forchheimer porous media amalgamated with quartic autocatalysis chemical reaction. Additional impacts added to the novelty of the mathematical model are the heat generation/absorption and buoyancy effect. The dimensionless variables led the envisaged mathematical model to a physical problem. The numerical solution is then found by engaging MATLAB built-in bvp4c function for non-dimensional velocity, temperature, and homogeneous-heterogeneous reactions. The validation of the proposed mathematical model is ascertained by comparing it with a published article in limiting case. An excellent consensus is accomplished in this regard. The behavior of numerous dimensionless flow variables including solid volume fraction, inertia coefficient, velocity ratio parameter, porosity parameter, slip velocity parameter, magnetic parameter, Schmidt number, and strength of homogeneous/heterogeneous reaction parameters are portrayed via graphical illustrations. Computational iterations for surface drag force are tabulated to analyze the impacts at the stretched surface. It is witnessed that the slip velocity parameter enhances the fluid stream velocity and diminishes the surface drag force. Furthermore, the concentration of the nanofluid flow is augmented for higher estimates of quartic autocatalysis chemical.

Optimization Research on Dynamic Balance of Spatial Engine under Limiting Shaking Moment

2009 ◽  
Vol 626-627 ◽  
pp. 693-698
Author(s):  
Yong Yong Zhu ◽  
S.Y. Gao
Keyword(s):  
Mathematical Model ◽  
Objective Function ◽  
Kinetic Analysis ◽  
Optimization Design ◽  
Design Method ◽  
Dynamic Balance ◽  
Optimized Design ◽  
Design Variables ◽  
The Mathematical Model ◽  
Shaking Moment

Dynamic balance of the spatial engine is researched. By considering the special wobble-plate engine as the model of spatial RRSSC linkages, design variables on the engine structure are confirmed based on the configuration characters and kinetic analysis of wobble-plate engine. In order to control the vibration of the engine frame and to decrease noise caused by the spatial engine, objective function is choosed as the dimensionless combinations of the various shaking forces and moments, the restriction condition of which presents limiting the percent of shaking moment. Then the optimization design is investigated by the mathematical model for dynamic balance. By use of the optimization design method to a type of wobble-plate engine, the optimization process as an example is demonstrated, it shows that the optimized design method benefits to control vibration and noise on the engines and improve the performance practically and theoretically.

scholarly journals Global effect of local skin friction drag reduction in spatially developing turbulent boundary layer

2016 ◽  
Vol 805 ◽  
pp. 303-321 ◽  
Author(s):  
A. Stroh ◽  
Y. Hasegawa ◽  
P. Schlatter ◽  
B. Frohnapfel
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Drag Reduction ◽  
Control Region ◽  
Reduction Rate ◽  
Wall Turbulence ◽  
Local Skin ◽  
Control Schemes ◽  
Local Skin Friction ◽  
Friction Drag Reduction

A numerical investigation of two locally applied drag-reducing control schemes is carried out in the configuration of a spatially developing turbulent boundary layer (TBL). One control is designed to damp near-wall turbulence and the other induces constant mass flux in the wall-normal direction. Both control schemes yield similar local drag reduction rates within the control region. However, the flow development downstream of the control significantly differs: persistent drag reduction is found for the uniform blowing case, whereas drag increase is found for the turbulence damping case. In order to account for this difference, the formulation of a global drag reduction rate is suggested. It represents the reduction of the streamwise force exerted by the fluid on a plate of finite length. Furthermore, it is shown that the far-downstream development of the TBL after the control region can be described by a single quantity, namely a streamwise shift of the uncontrolled boundary layer, i.e. a changed virtual origin. Based on this result, a simple model is developed that allows the local drag reduction rate to be related to the global one without the need to conduct expensive simulations or measurements far downstream of the control region.

The Function of Magnetic Field in a Magnetic-Electrochemical Compound Polishing

2010 ◽  
Vol 97-101 ◽  
pp. 4141-4145 ◽  
Author(s):  
Li Min Shi ◽  
Er Liang Liu ◽  
Yong Jiang Niu ◽  
Yu Quan Chen
Keyword(s):  
Magnetic Field ◽  
Mathematical Model ◽  
Concentration Polarization ◽  
Electrochemical Reaction ◽  
Charged Particles ◽  
Polishing Process ◽  
Electrical Field ◽  
Movement Model ◽  
The Mathematical Model ◽  
The Magnetic Field

Traditionally, the magnetic field is always vertical to the electrical field in a magnetic-electrochemical compound polishing.The magnetic field is set to parallel the electrical field in this paper. The mathematical model of the charged particles movement in a magnetic field is established through the analysis of its movement process when using Coulomb laws and Lorentz force. Through constructing the velocity formulation and loci formulation, the function of the magnetic field is proved. Because of the magnetic field, the concentration polarization of electrochemical reaction can be reduced more and the electrochemical reaction can be accelerated easily than the traditional polishing in which the magnetic field is vertical to the electrical field. Finally, to verify the model, the magnetic-electrochemical compound polishing process has been tested and the results, compared with those obtained from the model, have shown the movement model is reasonable and the analysis to function of magnetic field is correct.

Research on the Conformal Phased-Array Antenna

2014 ◽  
Vol 685 ◽  
pp. 324-327
Author(s):  
Shuang Zhao ◽  
Yu Bo Yue
Keyword(s):  
Mathematical Model ◽  
Antenna Array ◽  
Phased Array ◽  
Design Method ◽  
Array Antenna ◽  
Phased Array Antenna ◽  
Conformal Antenna ◽  
Conformal Array ◽  
Design Requirements ◽  
The Mathematical Model

The mathematical model of conformal antenna array is the premise and basis of the conformal array antenna signal processing. Based on the analysis of the antenna array, a design method for adjusting the direction of the conformal array antenna is proposed. Through simulation, the pattern of antenna meets the actual needs of the project and it reaches pre design requirements.

A Design Method for Analog and Digital Silicon Neurons ???-Mathematical-Model-Based Method-

2008 ◽  
Author(s):  
Takashi Kohno ◽  
Kazuyuki Aihara ◽  
Luigi M. Ricciardi ◽  
Aniello Buonocore ◽  
Enrica Pirozzi
Keyword(s):  
Mathematical Model ◽  
Design Method ◽  
Model Based ◽  
Silicon Neurons
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