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Three-dimensional VOF simulation of droplet impacting on a superhydrophobic surface

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Bio-Design and Manufacturing 2019年第1期2卷 10-23页

作者： Jin Sun Qi liu Yunhong Liang Zhaohua Lin chunbao liu School of Mechanical Science and Aerospace Engineering Jilin University Changchun 13002 China Key Laboratory of Bionic Engineering Ministry of Education Jilin University Changchun. China

It is very important to analyze and study the motion process of droplets impacting superhydrophobic surface, which is of great significanee to understand the mechanism of superhydrophobic surface and guide the design and manufacture of superhydrophobic surface. Taking by three-dimensional volume of fluid (VOF) simulation coupling coupled level set (CLS) algorithm, on the one hand, we simulate the morphological changes in the process of droplet impingement, as well as the internal velocity and the pressure distribution;on the other hand,we focus on the effects of droplet impact velocity, surface wettability, surface tension on the dynamics of the droplets. The CLSVOF model inherits the advantages of the VOF model for accurately constructing the phase interface and inherits the advantage that the level set can accurately calculate the surface tension, which improves the accuracy of the calculation of the droplet impact on the superhydrophobic surface. The computed results distinctly demonstrated there were four stages: falling, spreading, shrinking and rebounding. The time history of each stage agreed well with the pictures captured by high-speed camera, which indicated the computational fluid dynamics scheme was effective. Moreover, the motion mechanism of the droplets impacting on the solid surface is elaborated, which was helpful to control the solid-liquid interface to achieve a variety of solid interface characteristics.

关键词： Superhydrophobic Droplet impact Computational fluid dynamic VOF

Load-dependent Variable Gearing Mechanism of Muscle-like Soft Actuator

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Journal of Bionic Engineering 2022年第1期19卷 29-43页

作者： Yingjie Wang chunbao liu Luquan Ren Lei Ren School of Mechanical and Aerospace Engineering Jilin UniversityChangchun130022China Key Laboratory of Bionic Engineering Ministry of EducationJilin UniversityChangchun130022China School of Mechanical Aerospace and Civil EngineeringUniversity of ManchesterManchesterM139PLUK

Pennate muscle is characterized by muscle fibers that are oriented at a certain angle(pennation angle)relative to the muscle’s line of action and rotation during *** fiber rotation amplifies the shortening velocity of muscle,to match loading conditions without any control *** unique variable gearing mechanism,which characterized by Architecture Gear Ratio(AGR),is involves complex interaction among three key elements:muscle fibers,connective tissue,and the pennation ***,how three elements determine the AGR of muscle-like actuator is still *** study introduces a Himisk actuator that arranges five contractile units at a certain pennation angle in a flexible matrix,the experiment and simulation results demonstrated that the proposed actuator could vary AGR automatically in response to variable loading *** on this actuator,we present a series of actuators by simulations with the varying pennation angle(P),elastic modulus of the flexible matrix(E),and number of contractile units(N)to analyze their effects on AGR,and their interaction by three-factor analysis of *** results demonstrated that P and N effect on the AGR significantly,while E effects on AGR slightly,which supported the idea that the P is the essential factor for the AGR,and N is also an important factor due to the capability of force *** provides a better understanding of mechanical behavior and an effective optimizing strategy to muscle-like soft actuator.

关键词： Bioinspired Actuator Pennate muscle Gearing mechanism

A Review of Biological Fluid Power Systems and Their Potential Bionic Applications

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Journal of Bionic Engineering 2019年第3期16卷 367-399页

作者： chunbao liu Yingjie Wang Luquan Ren Lei Ren School of Mechanical and Aerospace Engineering Jilin University Changchun 130022 China Key Laboratory of Bionic Engineering Ministry of Education Jilin University Changchun 130022 China School of Mechanical Aerospace and Civil Engineering University of Manchester Manchester M13 9PL UK

Nature has always inspired human achievements in industry, and biomimetics is increasingly being applied in fluid power technology. Arachnida use hydraulic forces, rather than muscle, for leg extensions during locomotion. Many cold-blooded and soft-bodied organisms rely on a hydrostatic skeleton to transmit force, which involves a hydraulic mechanism. Biological hydraulic transmission differs from engineering hydraulic transmission in many aspects, such as in energy transfer and transformation, the movement mode, environmental friendliness, system pressure level, and energy supplement mode. The existence of a hydraulic mechanism in a biological drive requires 3 features: a power source, cavity, and working medium. The power source is similar to a hydraulic pump, and the cavity is similar to a hydraulic cylinder, both of which are necessary for producing deformation. The working medium is similar to a hydraulic fluid. Under these 3 conditions, a biological flow is generated inside or outside the body to meet the requirements of a biological drive. This paper reviews the biological organisms that employ hydraulic systems, identifies related studies on these biological hydraulic systems, and summarizes the mechanisms involved in using hydraulic pressure to achieve graceful and agile movements. This in-depth study and exploration of biological hydraulic systems can provide a good reference for solving the challenges of using hydraulic systems, such as increasing the energy efficiency, improving reliability, building smart components and systems, reducing the size and weight of components, reducing the environmental impact of systems, and improving and applying energy storage and redeployment capabilities. This paper also includes a detailed discussion of new ideas and innovative sources for the future development of hydraulic systems. In contrast with the bio-inspired designs used in other engineering fields, very few studies have reported on using bio-inspired methods

关键词： bionic fluid power pressurized liquids locomotion bio-inspired applications

Bioinspired soft actuators with highly ordered skeletal muscle structures

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Bio-Design and Manufacturing 2022年第1期5卷 174-188页

作者： Yingjie Wang chunbao liu Luquan Ren Lei Ren School of Mechanical and Aerospace Engineering Jilin UniversityChangchun 130022China School of Mechanical Aerospace and Civil EngineeringUniversity of ManchesterManchester M139PLUK Key Laboratory of Bionic Engineering Ministry of EducationJilin UniversityChangchun 130022China

Mammals such as humans develop skeletal muscles composed of muscle fibers and connective tissue,which have mechanical properties that enable power output with three-dimensional motion when *** muscle-like actuators developed to date,such as the McKibben artificial muscle,often focus sole contractile elements and have rarely addressed the contribution of flexible connective tissue that forms an integral part of the structure and morphology of biological ***,we present a class of pneumatic muscle-like actuators,termed highly mimetic skeletal muscle(HimiSK)actuator,that consist of parallelly arranged contractile units in a flexible matrix inspired by ultrasonic measurements on skeletal *** contractile units act as a muscle fiber to produce active shortening force,and the flexible matrix functions as connective tissue to generate passive *** application of positive pressure to the contractile units can produce a linear contraction and *** this actuator,we assign different flexible materials as contractile units and a flexible matrix,thus forming five mold *** actuators feature three-dimensional motion on activation and present both intrinsic force-velocity and force-length characteristics that closely resebmle those of a biological *** output and tetanic force produced by harder contractile units improve the maximum output force by up to about 41.3%and the tetanic force by up to about 168%.Moreover,high displacement and velocity can be generated by a softer flexible matrix,with the improvement of maximum displacement up to about 33.3%and velocity up to about 73%.The results demonstrate that contractile units play a crucial role in force generation,while the flexible matrix has a significant impact on force transmission and deformation;the final force,velocity,displacement,and three-dimensional motion results from the interplay of contractile units,fluid and flexible *** approach introduces a m

关键词： Bioinspired Soft robotics Actuator Skeletal muscle

Design and Optimization of Bionic Janus Blade in Hydraulic Torque Converter for Drag Reduction

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Journal of Bionic Engineering 2018年第1期15卷 160-172页

作者： chunbao liu Chuang Sheng Hualong Yang Zhe Yuan School of Mechanical Science and Engineering Jilin University Changchun 130022 China Key Laboratory of Bionic Engineering Ministry of Education Jilin University Changchun 130022 China State Key Laboratory of Automotive Simulation and Control Jilin University Changchun 130022 China

The chief aim of the present work was to achieve drag reduction in stator blades with liquid using boundary layer control. A stator blade of hydraulic torque converter with bionic grooves in suction side and hydrophobic surface in pressure side was designed. The hydrophobic surface was created using anodic oxidation method and irregular A1203 thin films were found on the surface. They formed hierarchical structure consisting of mini porous structures and microscopic pore spaces, resulting in the hydrophobicity. The bionic groove was designed by Computational Fluids Dynamics （CFD） method. Multi-Island Genetic Algorithm （MIGA） was adopted for groove multi-objective optimization. Through optimization, the maximum drag reduction was close to 12% in oil. In addition, the drag reduction calculation was verified by closed channel experiment and ＂Tire Vortex＂ was proposed to explain the drag reduction mechanism. The bionic Janus blade could maintain its initial profile without any additional device, which had lower risk and less cost. The results are encouraging and show great potential to apply in other flow machineries.

关键词： hydraulic torque converter bionic blade boundary layer control drag reduction

Rapid,Energy-saving Bioinspired Soft Switching Valve Embedded in Snapping Membrane Actuator

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Journal of Bionic Engineering 2023年第1期20卷 225-236页

作者： Fangzhou Zhao Yingjie Wang Sijia liu Miao Jin Luquan Ren Lei Ren chunbao liu School of Mechanical and Aerospace Engineering Jilin UniversityChangchun130022China Key Laboratory of Bionic Engineering Ministry of EducationJilin UniversityChangchun130022China School of Mechanical Aerospace and Civil EngineeringUniversity of ManchesterManchesterM139PLUK

In nature,organisms widely use the interaction of muscle contraction and biological pipelines to form an efficient fluid control ***,a pneumatically powered,Bioinspired Soft Switching valve(BSS valve)with short response time and low-energy consumption is *** BSS valve is composed of flexible walls,a flexible tube and symmetrically arranged Snapping Membrane actuator(SM actuator).It functions based on tube deformation throttling caused by instability of SM actuator *** realize rapid preparation of customized BSS valve,the modular manufacturing method suitable for different materials and structures based on 3D printing and mold forming was *** the membrane flip rate as indicators,the displacement transient response characteristics of three structures actuators were studied,The results proved that spherical and spherical cap membrane SM actuator achieved rapid displacement response under the low critical pressure ***,with critical buckling pressure and capacity utilization efficiency as indicators,we analyzed the characteristics of SM actuators with different radius and wall thickness to obtain reasonable structural parameters configuration of SM *** influence of radius and thickness on SM actuator is revealed,and theoretical model formulas were *** different configurations are presented.(1)Customized BSS valve structures can achieve sequential motion of flexible gripper.(2)BSS valve embedded in soft *** performance tests confirmed it has significant advantages in energy consumption,specific pressure,specific flow,high-frequency cycle load life,and valve can be integrated into the soft pump fluid system as a throttling unit,and provides an idea for fluid drive control integration.

关键词： Bioinspired.Soft robot BSS valve SM actuator

Fabrication of Bio-inspired Superamphiphobic Aluminum Alloy Surface with Oil-triggered Wenzel-Slippery Transition via Femtosecond Laser

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Journal of Bionic Engineering 2024年第3期21卷 1375-1387页

作者： Weijian liu Feng Guan Fulin Zhang Chenrui Wang Wei Zheng Lu Zhai Zhaohua Lin chunbao liu AVIC Shenyang Aircraft Corporation Shenyang110000China School of Mechanical and Aerospace Engineering Jilin UniversityChangchun130022China

Surface-tension-confined microfluidic devices are platforms for manipulating 2D droplets based on patterned surfaces with special *** have great potential for various applications,but are still in the early stages of development and face some challenges that need to be *** study,inspired by the Wenzel and slippery transition of rose petal,develops a Patterned Oil-triggered Wenzel-slippery Surface(POWS)to examine the microfluidic devices.A laser-chemical composite method is established to fabricate POWSs,which take rose-petal-like microstructures as wettability pattern and a superamphiphobic surface as the *** prepared POWSs switched between high adhesion superhydrophobic state and the slippery liquid-infused surface state through adding or removing the lubricant *** the high adhesion superhydrophobic state,the droplets can be sticked on the *** the slippery liquid-infused state,the droplet can slide along the wettability pattern as the designed route.A POWS-based droplet reactor is further constructed,on which,the droplets can be remotely controlled to move,mix and react,as *** a POWS,which manipulates droplets with surface tension controlled by the switchable wettability patterns,would be a promising candidate to construct multiple surface-tension-confined microfluidic *** addition,the fabrication technique and design principle proposed here may aid the development of various field related to the bio-inspired surfaces,such as water collection,desalination and high throughput analysis,etc.

关键词： Biomaterials Bio-inspired surface Oil-triggered wenzel-slippery transition Superhydrophobicity Femtosecondlaser

Stress-Blended Eddy Simulation of the Turbulent Flow Around Circular Cylinder with Dynamic Hybrid RANS/LES Model

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Journal of Beijing Institute of Technology 2019年第2期28卷 238-247页

作者： chunbao liu Jing Li Weiyang Bu Dong Xu Wen Wu Key Laboratory of Road Construction Technology and Equipment of MOE Chang'an UniversityXi'an 710064China School of Mechanical and Aerospace Engineering Jilin UniversityChangchun 130022China

In order to verify the effectiveness and superiority of the dynamic hybrid RANS/LES(DHRL)model,the flow around a cylinder with sinusoidal fluctuating velocity at the inlet was used as the test *** latest computational fluid dynamics(CFD)model can flexibly choose any existing large-eddy simulation(LES)method combined with RANS method to calculate the flow *** addition,the DLES model and DDES model are selected as typical representatives of the turbulence model to compare the capture ability of the flow field *** internal flow field including the y+value,velocity distribution,turbulent kinetic energy and vortex structures is comprehensively ***,the results show that the new model has enough sensitivity to capture the information of the flow field and has more consistent velocity distribution with the experimental value,which shows its potential in practical engineering applications to some extent.

关键词： dynamic hybrid RANS/LES(DHRL) turbulence flow around cylinder computational fluid dynamics(CFD)

Investigation of microstructure modification of C-doped a-SiO_2/Si after Pb-ion irradiation

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Science China(Physics,Mechanics & Astronomy) 2012年第2期55卷 242-246页

作者： liu chunbao WEI KongFang YAO CunFeng WANG ZhiGuang JIN YunFan TOULEMONDE M Department of Physics Heze UniversityHeze 274015China Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000China Centre for Interdisciplinary Research with Heavy lons Caen 14070France

Thermally grown amorphous SiO2 （a-SiOz） films were implanted at room temperature （RT） with 100 keV C-ions to 5.0× 10^17 ions/cm2. These samples were irradiated at RT with 853 MeV Pb-ions to 1.0x 1012 and 5.0× 10^12 ions/cm2. Then the samples were investigated using Transmission Electron Microscopy （TEM） at RT. Significant microstructure modifications were observed in C-doped a-SiO2/Si samples after high energy Pb-ion irradiations, and the formation of new structures depended strongly on the Pb-ion irradiation fluences. For example, tracks in high density were observed in a 1.0× 10^12 Pb/cm2 irradiated and C-doped sample. Additionally, the length of tracks grows, and a large number of 8H-SiC nanocrystals can be seen in the film when irradiation fluence is increased to 5.0× 10^12 Pb/cm2. Possible modification processes of C-doped a-SiO2 under swift heavy ion irradiations are briefly discussed.

关键词： swift heavy ion irradiation C-doped SiO2 Transmission Electron Microscopy (TEM)