Numerical Simulation of Micro Flow Field on Biomimetic Sharkskin Micro-Grooved Surface

2014 ◽  
Vol 884-885 ◽  
pp. 378-381 ◽  
Author(s):  
Yue Hao Luo ◽  
Yu Fei Liu
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Drag Reduction ◽  
Reduction Mechanism ◽  
Urgent Problem ◽  
Grooved Surface ◽  
Micro Flow ◽  
Important Significance

It is well-known that sharkskin surface has the effect of inhibiting the occurrence of turbulence and reducing the wall resistance, however, the drag reduction mechanism has developed into an urgent problem to be resolved now. According to the actual circumstance, for purpose of obtaining the best drag-reducing efficiency, the biomimetic sharkskin micro-grooved surface is designed according to the relevant literatures and research achievements, and numerical simulation of the micro flow field on the biomimetic sharkskin surface is carried out comprehensivley, which has the important significance to explain the drag reduction mechanism.

INFLUENCE OF MORPHOLOGY FOR DRAG REDUCTION EFFECT OF SHARKSKIN SURFACE

2014 ◽  
Vol 14 (02) ◽  
pp. 1450029 ◽  
Author(s):  
YUEHAO LUO ◽  
YUFEI LIU ◽  
DEYUAN ZHANG ◽  
E. Y. K. NG
Keyword(s):  
Natural Selection ◽  
Flow Field ◽  
Drag Reduction ◽  
Hydrophobic Effect ◽  
Academic Research ◽  
Engineering Application ◽  
Reduction Mechanism ◽  
Urgent Problem ◽  
Micro Flow ◽  
Reduction Effect

Through millions of years' natural selection, creature has formed their own unique functional surfaces. Shark is one of the fastest animals in the ocean, which is well known for "sharkskin effect". Sharkskin surface is all covered by tiny and rigid scales with sophisticated morphology, which is one important factor to produce the high drag reducing efficiency. However, the drag reduction mechanism of sharkskin has not been understood thoroughly, which has developed into an urgent problem to be resolved. In this paper, the accurate 3D digital model of sharkskin surface is constructed based on the biological prototype and the micro flow field on the near wall is analyzed comprehensively and deeply. In addition, the drag reduction mechanism is explored from different aspects, especially which, the influences of the variation of attack angles of scales, the super-hydrophobic effect and nanochain of mucus on drag-reducing efficiency are taken into consideration, which has great significance on academic research and engineering application.

Study of Truck’s Aerodynamic Drag Reduction Based on Jet

2014 ◽  
Vol 635-637 ◽  
pp. 316-319
Author(s):  
Peng Guo ◽  
Jun Yuan Zhang ◽  
Qi Fei Li ◽  
Xing Jun Hu
Keyword(s):  
Numerical Simulation ◽  
Comparative Analysis ◽  
Flow Field ◽  
Drag Reduction ◽  
Pressure Distribution ◽  
Aerodynamic Drag ◽  
Outer Flow ◽  
Air Movement ◽  
Maximum Drag Reduction ◽  
Aerodynamic Drag Reduction

Multiple schemes are adapted on truck's outer flow field based on numerical simulation. Comparative analysis with the state of air flow, the pressure distribution, the air movement between the cab and cargo is pursued, then obtain the effect of jet flow velocity to the truck Cd. With the increasing of the jet velocity, Cd increases first and then decreases. The maximum drag reduction can reaches 7.38%.

Influence of Jet Hole Configuration on Drag Reduction of Bionic Jet Surface

2013 ◽  
Vol 461 ◽  
pp. 725-730 ◽  
Author(s):  
Yun Qing Gu ◽  
Jing Ru ◽  
Zhao Gang ◽  
Zhao Yuan Li ◽  
Wen Bo Liu ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Drag Reduction ◽  
Reduction Rate ◽  
Experimental Tests ◽  
Isosceles Triangle ◽  
Hole Configuration ◽  
Field Velocity ◽  
Jet Velocity ◽  
Reduction Characteristics

According to the jet hole configuration mode of bionic jet surface and its influence on the drag reduction, as the basic form of jet hole configuration is the isosceles triangle elements, so this was used to establish the computational model of jet hole configuration. In this case, the height and base of the triangles were considered as variable. The SST k-ω turbulence model was used to simulate and research the drag reduction characteristics of bionic jet surface in different configuration modes of jet holes at the main flow field velocity value of 20m/s and the jet velocity value of 0.4~2.0m/s. Also the influence of different configurations of height and base on drag reduction characteristics of bionic jet surface was studied, which got the optimum size of jet hole configuration. Results show that in triangle configuration elements, the drag reduction characteristics of bionic jet surface can be influenced by the jet hole of different configurations of height and base; the drag reduction of bionic jet surface reaches the peak of 32.74% at 8mm height, 11mm base, and the jet velocity value of 2.0m/s. At the same flow field velocity, the drag reduction rate results achieved by experimental tests and by numerical simulation were changing consistently and were found same, which verifies correctness of numerical simulation results.

Numerical Simulation of Micro Flow Field of Micro Injector

2011 ◽  
Vol 327 ◽  
pp. 61-65
Author(s):  
Li Li Mu ◽  
Ning Xue
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Piezoelectric Ceramic ◽  
Calculation Model ◽  
Dynamic Evolution ◽  
Micro Channel ◽  
First Order ◽  
Micro Nozzle ◽  
Vof Model ◽  
Micro Flow

In order to research the effects of digital micro droplet injected by the piezoelectric ceramic inertial driver, the calculation model of micro flow field of micro injector was established based on the VOF model of multiphase flow. The calculation selected the implicit segregated solver and the standard k-e model was used in turbulence of the micro-nozzle. The governing equation was separated in first order upwind, and solved by PISO algorithm. The flow pattern of the micro channel fluid and the dynamic evolution process of the micro droplet generation in the plus wave driving were researched.

scholarly journals Grouting Fractured Coal Permeability Evolution Based on Industrial CT Scanning

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Li Tao ◽  
Yao Banghua ◽  
Liu Yong ◽  
Wang Dengke
Keyword(s):  
Numerical Simulation ◽  
Gas Extraction ◽  
Permeability Reduction ◽  
Reduction Mechanism ◽  
Coal Permeability ◽  
Grouting Pressure ◽  
Before And After ◽  
Industrial Ct ◽  
Fractured Coal ◽  
Important Significance

Gas extraction from coal seams in China faces various middle-term and long-term problems, such as the poor sealing quality and low extraction rate. The mean gas extraction concentration is only 30%. Studying the flowing laws of the grout and fracture plugging mechanism is of important significance to improve the sealing quality and increase the gas extraction efficiency. For this reason, a new coal-based grouting material was prepared in this study, and its parameters such as viscosity were tested. Moreover, a grouting theoretical model with considerations of the flowing of the grout and coal fracture plugging by migration and deposition of slurry particles was constructed. The crack distribution before and after the grouting of fractured coal samples was scanned with an industrial CT, and the fracture distribution of coal samples was reconstructed using an independently compiled MATLAB program. Meanwhile, the variations of the coal permeability before and after the grouting were tested. On this basis, this study built a numerical calculation model of the grouting in fractured coal samples to simulate the leakage stoppage and permeability reduction mechanism of the coal-based sealing material grouting. Results demonstrate that (1) according to the experimental test results, the new coal-based grouting materials achieve a good fracture plugging effect, and the fractures in coal samples after the grouting are filled densely by the grouting particles. (2) According to the simulation results, the permeability of grouting coal samples declines quickly and then tends to be stable. The overall permeability of coal samples and the fracture permeability are decreased by 93.5% and more than 99.9% in average, respectively. (3) Influences of the grouting pressure on the permeability variation of coal samples were investigated through a numerical simulation. It was found that a reasonable grouting pressure for coal samples is about 0.3 MPa. (4) The numerical simulation reproduces the whole process of the grout flowing and the fracture filling. The variation laws of the diffusion and the permeability of the grout which are calculated through a numerical simulation agree well with the experimental results, which verifies the reasonability of the model. Research conclusions can provide important significance in theory and practice to disclose the leakage stoppage and the permeability reduction mechanism of the borehole grouting during the gas extraction and strengthen the sealing effects of extraction boreholes.

scholarly journals Study on the Drag Reduction Characteristics of the Surface Morphology of Paramisgurnus dabryanus Loach

Coatings ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1357
Author(s):  
Liyan Wu ◽  
Jiaqi Wang ◽  
Guihang Luo ◽  
Siqi Wang ◽  
Jianwei Qu ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Boundary Layer ◽  
Drag Reduction ◽  
Reduction Rate ◽  
Underwater Vehicles ◽  
Flow Channel ◽  
Numerical Control ◽  
Reduction Mechanism ◽  
Paramisgurnus Dabryanus ◽  
Reduction Characteristics

The drag reduction design of underwater vehicles is of great significance to saving energy and enhancing speed. In this paper, the drag reduction characteristics of Paramisgurnus dabryanus loach was explored using 3D ultra-depth field microscopy to observe the arrangement of the scales. Then, a geometric model was established and parameterized. A simulated sample was processed by computer numerical control (CNC) machining and tested through using a flow channel bench. The pressure drop data were collected by sensors, and the drag reduction rate was consequently calculated. The test results showed that the drag reduction rate of a single sample could reach 23% at a speed of 1.683 m/s. Finally, the experimental results were verified by numerical simulation and the drag reduction mechanism was explored. The boundary layer theory and RNG k-ε turbulence model were adopted to analyze the velocity contour, pressure contour and shear force contour diagrams. The numerical simulation results showed that a drag reduction effect could be achieved by simulating the microstructure of scales of the Paramisgurnus dabryanus loach, showing that the results are consistent with the flow channel experiment and can reveal the drag reduction mechanism. The bionic surface can increase the thickness of boundary layer, reduce the Reynolds number and wall resistance. The scales disposition of Paramisgurnus dabryanus loach can effectively reduce the surface friction, providing a reference for future research on drag reduction of underwater vehicles such as ships and submarines.

CHEMICAL, MECHANICAL AND HYDRODYNAMIC PROPERTIES RESEARCH ON COMPOSITE DRAG REDUCTION SURFACE BASED ON BIOLOGICAL SHARKSKIN MORPHOLOGY AND MUCUS NANOLONG CHAIN

2015 ◽  
Vol 15 (05) ◽  
pp. 1550084 ◽  
Author(s):  
YUEHAO LUO ◽  
DEYUAN ZHANG ◽  
YUFEI LIU ◽  
YUANYUE LI ◽  
E. Y. K. NG
Keyword(s):  
Natural Selection ◽  
Drag Reduction ◽  
Water Tunnel ◽  
Reduction Mechanism ◽  
Hydrodynamic Properties ◽  
The World ◽  
Smooth Skin ◽  
Survival Of The Fittest ◽  
Important Significance ◽  
Long Chain

Natural selection, survival of the fittest. Through millions of years' evolution, shark has become one of the fastest swimming animals in the ocean, and it is very well-known for sharkskin effect, especially for "sharkskin swimsuit". Due to its great superior properties in drag reduction, anti-wear, self-cleaning and so on, the investigations on the essential mechanisms and fabricating methods have attracted so much attention from all over the world, and the achievements have been widely put into application in industry, agriculture, transportation, airspace and so on, and so lots of profits have been obtained so far. In this paper, the method of fabricating artificial composite drag reduction surface based on biological sharkskin morphology and mucus nano-long chain is investigated and studied, the chemical, mechanical and hydrodynamic properties are explored from different aspects in depth, in which, the experimental results in water tunnel showed that the drag-reducing efficiency could surpass 20% with the smooth skin as reference, and the drag reduction mechanism is systematically explained and discussed from different aspects, which has important significance to understand the recent research status and expand the applications of sharkskin in the fluid engineering.

Numerical Simulation of Influence of Different Deflectors on Aerodynamic Characteristics of the Heavy Duty Truck

2013 ◽  
Vol 365-366 ◽  
pp. 474-477
Author(s):  
Yu Kun Liu ◽  
Qi Fei Li ◽  
Guan Qun Li ◽  
Ao Liu ◽  
Xing Jun Hu
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Drag Reduction ◽  
Aerodynamic Drag ◽  
Optimal Solution ◽  
Aerodynamic Characteristics ◽  
Heavy Duty ◽  
Heavy Duty Truck

In order to reduce the aerodynamic drag of heavy-duty truck, four different shape and style of deflectors based on the original one are added. With the method of numerical simulation, the influence of deflector on the flow field of the cab and the vehicle was analyzed, and the mechanism of aerodynamic drag and the measures of drag reduction were discussed in the study. When driving at speed of 30m/s, the aerodynamic drag will be significantly reduced with the contributions of all the four deflectors. The optimal solution can reach a reduction about 14%.

The Influence of Polymers on Coherent Structures in Decaying Homogeneous Isotropic Turbulence

2010 ◽  
Author(s):  
Wei-Hua Cai ◽  
Hong-Na Zhang ◽  
Feng-Chen Li
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Drag Reduction ◽  
Coherent Structures ◽  
Isotropic Turbulence ◽  
Polymer Additives ◽  
Fine Scale ◽  
Reduction Mechanism ◽  
Homogeneous Isotropic Turbulence ◽  
Increase Rate

Drag reduction in decaying homogeneous isotropic turbulence (DHIT) with polymer additives has been observed, which leads to weaker turbulent characteristic quantities. Coherent structures play an important role in the understanding of turbulent dynamics, and the introduction of polymer additives can significantly modify their behavior. It is believed the modifications are closely related to drag reduction mechanism. In the present study, we mainly focus on investigating the influence of polymers on coherent structures from phenomenological and energetic viewpoint for DHIT with polymers based on direct numerical simulation (DNS). The results show that polymers can not only suppress the increase rate of the enstrophy and strain but also their productions, leading to a remarkable inhibition of coherent structures especially at fine scale.

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