Calvin Hong Li^a, G. P. Peterson^b,*

Frontiers in Heat and Mass Transfer, Vol.1, No.2, pp. 1-10, 2010, DOI:10.5098/hmt.v1.2.3007

Abstract An experimental investigation of the Critical Heat Flux (CHF) and heat transfer coefficient (HTC) of two-phase heat transfer of de-Ionized (DI) water, pool boiling was conducted using several kinds of sintered copper microparticle porous uniform and modulated structures. The modulated porous structure reached a heat flux of 450 W/cm² and a heat transfer coefficient of 230,000 W/m2K. The thick and thin uniform porous structures achieved CHFs of 290 W/cm² and 227 W/cm² , respectively, and heat transfer coefficients of 118,000 W/m²K and 104,000 W/m²K. The mechanisms for the dramatically improved CHFs and HTCs were identified with assistance of a visualization… More >

Hai Trieu Phan^b, Nadia Caney^a,†, Philippe Marty^a, Stéphane Colasson^b, Jérôme Gavillet^b

Frontiers in Heat and Mass Transfer, Vol.2, No.1, pp. 1-6, 2011, DOI:10.5098/hmt.v2.1.3002

Abstract Experiments were performed to study the effects of surface wettability on flow boiling of water at atmospheric pressure. The test channel is a single rectangular channel 0.5 mm high, 5 mm wide and 180 mm long. The mass flux was set at 100 and 120 kg/m² s and the base heat flux was varied from 30 to 80 kW/m². Water enters the test channel under subcooled conditions. The sample surfaces are titanium (Ti) and diamond-like carbon (DLC) surfaces having a contact angle of 49° and 63°, respectively. The experimental results show different flow patterns that impact the heat transfer significantly.… More >

Xudong Chen^1,2, Quanzi Yuan^1,2,*

The International Conference on Computational & Experimental Engineering and Sciences, Vol.27, No.4, pp. 1-1, 2023, DOI:10.32604/icces.2023.09318

Abstract The wetting and instability of liquids on the surface of soluble solids is a problem of interface stability at multiple scales, which is coupled by mechanics and chemistry. This problem is crucial to application fields such as micro-nano processing and microscopic observation. In this work, the instability process of moving contact lines on the surfaces of soluble solids is investigated in experiments, theories, and simulations. Based on the unique shapes of the surfaces of soluble solids caused by instability in experiments, the concept of pagoda instability is proposed. Then the Cahn-Hilliard interfaces are developed to establish the evolution model of… More >

Sally M. Smith^*, Brenton S. Taft^† , Jacob Moulton

Frontiers in Heat and Mass Transfer, Vol.5, pp. 1-9, 2014, DOI:10.5098/hmt.5.6

Abstract This study investigates the wettability of fluid-solid interactions of interest for oscillating heat pipe (OHP) applications. Measurements were taken using two techniques: the sessile drop method and capillary rise at a vertical plate. Tested surface materials include copper, aluminum, and Teflon PFA. The working fluids tested were water, acetone, R-134a, and HFO-1234yf. A novel low-pressure experimental setup was developed for refrigerant testing. Results show that the refrigerants have significantly lower hysteresis than the water and acetone-based systems, which is thought to lead to better heat transfer in OHP design. More >

Mohammed Bourega^*, Ibrahim Kromba, Khadidja Fellah Arbi, Sofiane Soulimane

FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.10, pp. 2471-2480, 2023, DOI:10.32604/fdmp.2023.028661

Abstract This study uses a T-junction to examine the effects of different parameters (velocity ratio, viscosity, contact angle, and channel size ratio) on the generation of microdroplets, related rate, and size. More specifically, numerical simulations are exploited to investigate situations with a velocity varying from 0.004 to 1.6 m/s for the continuous phase and from 0.004 to 0.8 m/s for the dispersed phase, viscosity ratios (0.668, 1, 6.689, 10, 66.899), contact angle 80° < θ < 270° and four different canal size ratios (1, 1.5, 2 and 4). The results show that canal size influences droplet size and the generation rate.… More > Graphic Abstract

Dongmin Wang^1,2,*, Gaoshuai Lin¹

CMES-Computer Modeling in Engineering & Sciences, Vol.137, No.1, pp. 299-318, 2023, DOI:10.32604/cmes.2023.027280

Abstract There are five most widely used contact angle schemes in the pseudopotential lattice Boltzmann (LB) model for simulating the wetting phenomenon: The pseudopotential-based scheme (PB scheme), the improved virtual-density scheme (IVD scheme), the modified pseudopotential-based scheme with a ghost fluid layer constructed by using the fluid layer density above the wall (MPB-C scheme), the modified pseudopotential-based scheme with a ghost fluid layer constructed by using the weighted average density of surrounding fluid nodes (MPB-W scheme) and the geometric formulation scheme (GF scheme). But the numerical stability and accuracy of the schemes for wetting simulation remain unclear in the past. In… More >

Liang Yang^*, Tianle Xi, Zhixing Wang

FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.6, pp. 1585-1608, 2023, DOI:10.32604/fdmp.2023.024987

Abstract The VOF method is used to simulate the dynamics of a droplet interacting with a structure consisting of an array of microcolumns mounted on a flat surface. Such a specific configuration is intended to mimic the typical properties of lotus leaves, which typically display regularly arranged micron-scale papillary structures. After setting the initial velocity of the simulated droplet on the basis of practical considerations, an analysis is conducted about the effect of the characteristic size of the microstructure on the apparent contact angle. The pressure variation in the microstructure caves is also examined. The simulation results show that the change… More >

Qingmin Pan¹, Yongzong Lu¹, Liang Xue², Yongguang Hu^1,*

Phyton-International Journal of Experimental Botany, Vol.92, No.2, pp. 411-421, 2023, DOI:10.32604/phyton.2022.023437

Abstract The wettability of leaf surface, commonly represented by contact angle (CA), affects various physiological and physical processes. The present study aims to better understand the wettability of tea leaves and elucidate its influence on the energy barrier of the droplet condensation process. The CA values of different leaf ages (young, mature and old) of five famous tea cultivars (Maolu, longjing 43, Huangjinya, Zhongcha 108 and Anji Baicha) were measured via the sessile drop method, and the micro-morphology of two cultivars leaves (Maolu, Zhongcha 108) was investigated by a 3D super depth-of-field digital microscope. Specifically, two radically distinctive types of CA… More >

D. Shaw, W.L. Su

The International Conference on Computational & Experimental Engineering and Sciences, Vol.18, No.3, pp. 85-86, 2011, DOI:10.3970/icces.2011.018.085

Abstract The contact angle affects the life and accuracy of a linear gudieway. In this study, the factors which effect the angle of contact angle of linear guideway includes contact deformation of balls and grooves, downward load, ball diameter, number of load-carrying balls, number of load-carrying rows and conformity. A theoretical approach for finding the contact angle changed of linear gudieway is proposed by using Hertzian theory and Lundeberg/Palmgren approach. The results are useful for modification of loading capability of linear gudieway under load and different preload setting. More >

S. Aland¹, J. Lowengrub², A. Voigt¹

CMES-Computer Modeling in Engineering & Sciences, Vol.57, No.1, pp. 77-108, 2010, DOI:10.3970/cmes.2010.057.077

Abstract We present a new method for simulating two-phase flows in complex geometries, taking into account contact lines separating immiscible incompressible components. We combine the diffuse domain method for solving PDEs in complex geometries with the diffuse-interface (phase-field) method for simulating multiphase flows. In this approach, the complex geometry is described implicitly by introducing a new phase-field variable, which is a smooth approximation of the characteristic function of the complex domain. The fluid and component concentration equations are reformulated and solved in larger regular domain with the boundary conditions being implicitly modeled using source terms. The method is straightforward to implement… More >