scholarly journals Self-propulsion dynamics of small droplets on general surfaces with curvature gradient

2021 ◽  
Vol 33 (8) ◽  
pp. 082107
Author(s):  
Yujuan Chen ◽  
Xianmin Xu
Keyword(s):  
Curvature Gradient

Corneal Curvature Gradient Map: A New Corneal Topography Map to Predict the Corneal Healing Process

2014 ◽  
Vol 30 (3) ◽  
pp. 202-207 ◽  
Author(s):  
Paolo Vinciguerra ◽  
Cynthia J. Roberts ◽  
Elena Albé ◽  
Mario R. Romano ◽  
Ashraf Mahmoud ◽  
...  
Keyword(s):  
Healing Process ◽  
Corneal Topography ◽  
Corneal Curvature ◽  
Curvature Gradient

scholarly journals Bioinspired triangular patterns for water collection from fog

2019 ◽  
Vol 377 (2150) ◽  
pp. 20190128 ◽  
Author(s):  
Dong Song ◽  
Bharat Bhushan
Keyword(s):  
Pressure Gradient ◽  
Science And Technology ◽  
Laplace Pressure ◽  
Theme Issue ◽  
Droplet Motion ◽  
Triangular Shape ◽  
Conical Shape ◽  
Bioinspired Materials ◽  
Water Collection ◽  
Curvature Gradient

Cacti use spines with conical geometry to transport water to its base. A conical shape with curvature gradient generates a Laplace pressure gradient along the droplet, which is responsible for droplet motion. In this study, the triangular shape was used which also generates a Laplace pressure gradient along the droplet. A bioinspired surface, composed of a hydrophilic triangular pattern surrounded by a rim of superhydrophobic region, was used to transport water collected from the fog on the hydrophilic pattern. The growing droplets start to coalesce into bigger ones. Eventually, they are big enough to touch the superhydrophobic borders, which trigger the transport motion. Droplet mobility and water collection measurements were made on triangular patterns with various geometries to determine the most efficient configurations. Results from this study can be used to enhance the performance of water collection systems from fog. This article is part of the theme issue ‘Bioinspired materials and surfaces for green science and technology (part 2)’.

scholarly journals Bioinspired conical design for efficient water collection from fog

2019 ◽  
Vol 377 (2150) ◽  
pp. 20190125 ◽  
Author(s):  
Dev Gurera ◽  
Bharat Bhushan
Keyword(s):  
Pressure Gradient ◽  
Laplace Pressure ◽  
Surface Slope ◽  
Water Droplets ◽  
Theme Issue ◽  
Conical Shape ◽  
Gravitational Forces ◽  
Water Collection ◽  
Curvature Gradient ◽  
First Time

Nature is known for using conical shapes to transport the collected water from fog for consumption or storage. The curvature gradient of the conical shape creates a Laplace pressure gradient in the water droplets which drives them towards the region of lower curvature. Linear cones with linearly increasing radii have been studied extensively. A smaller tip angle cone transports water droplets farther because of higher Laplace pressure gradient. Whereas a larger tip angle with a larger surface slope transports water droplets because of higher gravitational forces. In this study, for the first time, a nonlinear cone with a concave profile has been designed with small tip angle and nonlinearly increasing radius to maximize water collection. This article is part of the theme issue ‘Bioinspired materials and surfaces for green science and technology (part 2)’.

An Experimental Investigation of Flow Characteristics Downstream of Discrete Film Cooling Holes on Turbine Blade Leading Edge

2011 ◽  
Vol 383-390 ◽  
pp. 5553-5560
Author(s):  
Shao Hua Li ◽  
Hong Wei Qu ◽  
Mei Li Wang ◽  
Ting Ting Guo
Keyword(s):  
Turbine Blade ◽  
Film Cooling ◽  
Flow Characteristics ◽  
Leading Edge ◽  
Suction Side ◽  
Wall Region ◽  
Pressure Side ◽  
Blowing Ratio ◽  
Curvature Gradient ◽  
Film Cooling Holes

The gas turbine blade was studied on the condition that the mainstream velocity was 10m/s and the Renolds number based on the chord length of the blade was 160000.The Hot-film anemometer was used to measure the two-dimension speed distribution along the downstream of the film cooling holes on the suction side and the pressure side. The conclusions are as follows: When the blowing ratio of the suction side and the pressure side increasing, the the mainstream and the jet injection mixing center raising. Entrainment flow occurs at the position where the blade surface with great curvature gradient, simultaneously the mixing flow has a wicked adhere to the wall. The velocity gradient of the u direction that on the suction side increase obviously, also the level of the wall adherence is better than the pressure side. With the x/d increasing, the velocity u that on the pressure side gradually become irregularly, also the secondary flow emerged near the wall region where the curvature is great. The blowing ratio on the suction side has a little influence on velocity v than that on the pressure side.

Experimental Study of Evaporation in the Contact Line Region of a Thin Film of Hexane

1985 ◽  
Vol 107 (1) ◽  
pp. 182-189 ◽  
Author(s):  
P. C. Wayner ◽  
C. Y. Tung ◽  
M. Tirumala ◽  
J. H. Yang
Keyword(s):  
Liquid Film ◽  
Contact Line ◽  
Thin Liquid Film ◽  
Bulk Composition ◽  
Transport Processes ◽  
Shear Stresses ◽  
Strong Function ◽  
Thickness Profile ◽  
Line Region ◽  
Curvature Gradient

The transport processes in the contact line region (junction of evaporating thin liquid film, vapor, and substrate) of stationary steady-state evaporating thin films of hexane with various bulk compositions were studied experimentally. The substrate temperature distribution and liquid film thickness profile were measured, analyzed, and compared with previous results on other systems. The results demonstrate that small changes in the bulk composition significantly alter the characteristics of the transport processes in the contact line region. The curvature gradient at the liquid-vapor interface is a strong function of evaporation rate and composition. Concentration and temperature gradients give interfacial shear stresses and flow patterns that enhance contact line stability.

scholarly journals Modified Artificial Bee Colony Algorithm with Multilevel Threshold Segmentation and Boundaries Evaluation for Shadow Detection

2019 ◽  
Vol 8 (11) ◽  
pp. 1395-1399
Keyword(s):  
Artificial Bee Colony Algorithm ◽  
Artificial Bee Colony ◽  
Data Preprocessing ◽  
Shadow Detection ◽  
Threshold Segmentation ◽  
Bee Colony ◽  
Response Gradient ◽  
Curvature Gradient ◽  
Edge Response

The appearance of shadows typically causes severe problems in pc vision. There are various methods have already put forward but scope in this field is open. In this article Shadow Detection and Removal Using Modified artificial bee colony (MABC) Algorithm with Multilevel Threshold segmentation is proposed. The proposed method uses three threshold and corresponding boundaries, associated curvature, edge response, gradient, and MABC algorithm. First data preprocessing is applied to find the correlation between the pixels then three threshold and corresponding boundaries evaluated to accurately differentiate pixels as foreground. The edge response, curvature, gradient are applied to find the boundaries. Finally, MABC has been applied for detecting the shadow. The results show improvement in comparison with other existing methods

scholarly journals Multi-point forming springback compensation control oftwo-dimensional hull plate

2020 ◽  
Vol 12 (4) ◽  
pp. 168781402091609 ◽  
Author(s):  
Shaojuan Su ◽  
Yuchao Jiang ◽  
Yeping Xiong
Keyword(s):  
Numerical Simulation ◽  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Technical Problem ◽  
Bending Moment ◽  
Correction Coefficient ◽  
Springback Compensation ◽  
Compensation Control ◽  
Curvature Gradient

Springback is always a technical problem in sheet metal forming. In this article, the rapid springback compensation control of two-dimensional hull plate is realized by theoretical calculation and numerical simulation. For the cylindrical shell, according to the bending forming theory of medium and thick plates, the total elastic-plastic bending moment is established, and the curvature change before and after springback is deduced. The curvature correction coefficient is determined by the precise numerical simulation technology. At the same time, the validity of the method is verified by cold bending experiment. For the shell with variable curvature, it is divided into several cylindrical surfaces according to the curvature gradient of its geometric section line. The compensation curvature array is obtained by the correction compensation algorithm of springback curvature of cylindrical plate, and the algorithm is verified by numerical simulation. The results show that the method is very close to the expected results. Thus, the efficiency and precision of forming will be improved, and the foundation of digitization of sheet metal forming is established.

Surfactant-Induced Formation of Honeycomb Pattern on Micropipette with Curvature Gradient

Langmuir ◽  
2011 ◽  
Vol 27 (9) ◽  
pp. 5410-5419 ◽  
Author(s):  
Xiaoli Jiang ◽  
Tianzhu Zhang ◽  
Lina Xu ◽  
Changling Wang ◽  
Xuefeng Zhou ◽  
...  
Keyword(s):  
Curvature Gradient ◽  
Honeycomb Pattern

Dual-Solution and Choked Flow Treatment in a Streamline Curvature Throughflow Solver

2011 ◽  
Author(s):  
Prashant Tiwari ◽  
Alex Stein ◽  
Yu-Liang Lin
Keyword(s):  
Supersonic Flow ◽  
Dual Solution ◽  
Gradient Term ◽  
Transonic Flows ◽  
Choked Flow ◽  
Streamline Curvature ◽  
Short Period ◽  
Curvature Gradient ◽  
Suitable Technique ◽  
Flow Treatment

In most turbomachinery design systems streamline curvature based throughflow calculations makes the backbone of aero design process. The fast, reliable and easy to understand solution is especially useful in performing several multistage design iterations in a short period of time. Although the streamline curvature based technique enjoys many benefits for subsonic applications there are some challenges for transonic and supersonic flow applications, which is the focus of this paper. In this work it is concluded that three key improvements are required to handle transonic flows in a streamline curvature throughflow solver. These are: 1) ability to overcome dual sub- and supersonic solution and guide the solver towards supersonic flow solution where applicable; 2) suitable technique to calculate the streamline curvature gradient term which can avoid singularity at sonic meridional Mach number and high gradient values in transonic flows; 3) suitable technique to handle choked flow in the turbomachinery flowpath. Solution procedures for “dual-solution” and choked flow treatment are new and developed as part of this work. However, procedure for calculating streamline curvature gradient is leveraged from earlier work done by Denton [1] and Came [2]. Implementation of these improvements is performed in a streamline curvature based throughflow solver. Numerical improvements presented here have been tested for a range of compressor and turbine cases (both subsonic and supersonic). It is shown that the numerical improvements presented in this paper resulted in an enhanced version of streamline curvature throughflow solver. The new code produces consistent solution for subsonic applications with no sacrifice in accuracy of the solver. However, considerable robustness improvements are achieved for transonic turbine cases.

Sign in / Sign up

Export Citation Format

Share Document