H. Azoui¹, D. Bahloul^1,*, N. Soltani²

FDMP-Fluid Dynamics & Materials Processing, Vol.14, No.2, pp. 87-105, 2018, DOI: 10.3970/fdmp.2018.01149

Abstract In this work we have performed a three-dimensional numerical investigation in order to find the optimal conditions for growing efficiently high quality sapphire crystals with good thermal properties. We have studied thermal instabilities near the melt-crystal interface and the convective heat transfer under the Czochralski (Cz) process. We performed 3-D CFD simulation in cylindrical coordinates and used the Fast Fourier Transform method to analyze the temperature fluctuations. We present a detailed investigation on the effects of the crystal rotation speed and the temperature distribution on thermal instabilities of sapphire melt under forced convection. Where the melt forced convection, the radiative… More >

S. Aggoune¹, C. Abid², E.H. Amara^1,3

FDMP-Fluid Dynamics & Materials Processing, Vol.11, No.2, pp. 115-125, 2015, DOI:10.3970/fdmp.2015.011.115

Abstract This paper focuses on the vortex formation effect during the application of a laser-fusion cutting technique. This industrial technique is typically associated with the ejection of a film of molten stainless steel blown off by a subsonic laminar jet of nitrogen gas used to assist the process. Without taking into account the transverse movement of the workpiece, we consider a 4 mm thick stainless steel plate. The resulting molten metal flow is assumed to be laminar, steady, viscous and incompressible. The numerical results reveal vortex structures adjacent to the walls at the entrance of the kerf, and a pair of… More >

V. Shevtsova^1,2, A. Mialdun¹, C. Ferrera^1,4, M. Ermakov^3,4, J. M. Montanero⁴

FDMP-Fluid Dynamics & Materials Processing, Vol.4, No.1, pp. 43-54, 2008, DOI:10.3970/fdmp.2008.004.043

Abstract Dynamic free surface deformations induced by buoyant and thermocapillary convection in liquid bridges of 5cSt silicone oil are studied experimentally and numerically. The experiments are performed in ground conditions and static deformation is unavoidable. Convective motion starts in the liquid bridge as soon as ΔT ≠ 0 and initially leads to a stationary dynamic deformation of the free surface. Oscillatory motion starts at a critical value of ΔT and causes oscillations of the interface. The final supercritical shape of the free surface is a result of the static shape with superimposed subcritical stationary and oscillatory dynamic deformations. All these contributions… More >

M.H. Djavareshkian¹, M. Khalili²

FDMP-Fluid Dynamics & Materials Processing, Vol.2, No.4, pp. 299-308, 2006, DOI:10.3970/fdmp.2006.002.299

Abstract This paper opens a new horizon on the simulation of sloshing phenomena. One of the most popular Finite Volume methods called VOF (Volume Of Fluid) method is used for tracking the flow in containers. The algorithm is tested for different fluid elevations, physical conditions in different road curves and liquid properties. The method is then validated against an analytical and another numerical solution. These comparisons show that the VOF can effectively solve the sloshing problem for different fluids and a variety of physical and geometrical conditions. More >

Marcello Lappa¹

FDMP-Fluid Dynamics & Materials Processing, Vol.1, No.2, pp. 171-188, 2005, DOI:10.3970/fdmp.2005.001.171

Abstract The paper presents a comparative and critical analysis of some theoretical/experimental/numerical arguments concerning the possible stabilization of the surface-tension-driven (Marangoni) flow in the Floating Zone technique and in various related fluid-dynamic models. It is conceived as a natural extension of the focused overview published in Cryst. Res. Tech. 40(6), 531, (2005) where much room was devoted to discuss the intrinsic physical mechanisms responsible for three-dimensional and oscillatory flows in a variety of technological processes. Here, a significant effort is provided to illustrate the genesis of possible control strategies (many of which are still in a very embryonic condition), the underlying… More >

K.H. Chen^1,2, J.H. Kao³, J.T. Chen⁴

CMC-Computers, Materials & Continua, Vol.9, No.3, pp. 253-280, 2009, DOI:10.3970/cmc.2009.009.253

Abstract In this paper, solving antiplane piezoelectricity problems with multiple inclusions are attended by using the regularized meshless method (RMM). This is made possible that the troublesome singularity in the MFS disappears by employing the subtracting and adding-back techniques. The governing equations for linearly electro-elastic medium are reduced to two uncoupled Laplace's equations. The representations of two solutions of the two uncoupled system are obtained by using the RMM. By matching interface conditions, the linear algebraic system is obtained. Finally, typical numerical examples are presented and discussed to demonstrate the accuracy of the solutions. More >

H.-S. Wang^1,2, H. Jiang^3,4, B. Yang²

CMC-Computers, Materials & Continua, Vol.51, No.3, pp. 145-161, 2016, DOI:10.3970/cmc.2016.051.145

Abstract Potential field due to line sources residing on slender heterogeneities is involved in various areas, such as heat conduction, potential flow, and electrostatics. Often dipolar line sources are either prescribed or induced due to close interaction with other objects. Its calculation requires a higher-order scheme to take into account the dipolar effect as well as net source effect. In the present work, we apply such a higher-order line element method to analyze the potential field with cylindrical slender heterogeneities. In a benchmark example of two parallel rods, we compare the line element solution with the boundary element solution to show… More >

Bui Duc Thuan^1,2, Wong Yonghui², Chua Kian Jon², Ng Kim Choon²

CMC-Computers, Materials & Continua, Vol.47, No.2, pp. 89-105, 2015, DOI:10.3970/cmc.2015.047.089

Abstract The cup method and dynamic moisture permeation cell (DMPC) method are two common techniques used to determine the water vapor permeation properties of a membrane. Often, ignoring the resistance of boundary air layers to the transport of water vapor results in the water vapor permeance of the membrane being underestimated in practical tests. The measurement errors are higher with highly permeable membranes. In this study, the two methods were simulated using COMSOL Multiphysics platform and the extent of the error was evaluated. Initial results showed that the error is equally high in both methods. With the correction for the still… More >

Ang Li¹, Guo-jian Shao^1,2, Pei-rong Du³, Sheng-yong Ding¹, Jing-bo Su⁴

CMC-Computers, Materials & Continua, Vol.45, No.1, pp. 17-38, 2015, DOI:10.3970/cmc.2015.045.017

Abstract This paper investigates the failure behaviors of stratified rocks under uniaxial compression using a digital image processing (DIP) based finite difference method (FDM). The two-dimensional (2D) mesostructure of stratified rocks, represented as the internal spatial distribution of two main rock materials (marble and greenschist), is first identified with the DIP technique. And then the binaryzation image information is used to generate the finite difference grid. Finally, the failure behaviors of stratified rock samples are simulated by FDM considering the inhomogeneity of rock materials. In the DIP, an image segmentation algorithm based on seeded region growing (SRG) is proposed, instead of… More >

P.A. Meroño¹, F.C. Gómez², F. Marín³

CMC-Computers, Materials & Continua, Vol.44, No.2, pp. 85-104, 2014, DOI:10.3970/cmc.2014.044.085

Abstract The measurement of torsional vibration is a common practice in certain fields, such as the automotive industry, power generation, or large alternative engines. Similarly, functional analysis and diagnostic of other equipment, which are not traditionally measured, can benefit greatly from this type of measurement. This review discusses some techniques used in industry to measure torsional vibration, briefly describing the types of sensors used and the transduction procedures. Choosing the most appropriate technique in each case not only responds to economic reasons, but also to other conditions of the given equipment, such as its design, coupled machines or devices, functional status… More >