Numerical simulation of single droplet dynamics in three-phase flows using ISPH

In this study, a new surface tension formulation for modeling incompressible, immiscible three-phase fluid flows in the context of incompressible smoothed particle hydrodynamics (ISPH) in two dimensions has been proposed. A continuum surface force model is employed to transform local surface tension force to a volumetric force while physical surface tension coefficients are expressed as the sum of phase specific surface tension coefficients, facilitating the implementation of the proposed method at triple junctions where all three phases are present. Smoothed color functions at fluid interfaces along with artificial particle displacement throughout the computational domain are combined to increase accuracy and robustness of the model. In order to illustrate the effectiveness of the proposed method, several numerical simulations have been carried out and results are compared to analytical data available in literature. Results obtained by simulations are compatible with analytical data, demonstrating that the ISPH scheme proposed here is capable of handling three-phase flows accurately

Liquid phase diffusion growth of SiGe single crystals under magnetic fields

The manuscript presents the results of a combined experimental and modeling study on the Liquid Phase Diffusion (LPD) growth of single crystal SixGe1-x on Germanium with and with the application of magnetic fields. Although the LPD process is mainly diffusion driven through out the growth period, strong natural thermosolutal convection occurs in the first five hours of growth, and the growth interface is concave to the melt. Applied rotating and static magnetic fields were considered to examine the growth and silicon dissolution processes in the LPD system. Results show that the application of a combined applied magnetic is beneficial

Numerical investigation of three-phase flows using incompressible smoothed particle hydrodynamics

An ISPH method for the simulation of three-phase °ows is presented in this article. The proposed method is investigated through the simulation of a droplet located at the interface of two immiscible °uids as well as diamond droplet deformation. The extendibility of the proposed surface tension formulations for three-phase fows to two-phase fows is also investigated. It is observed that the results obtained from the numerical simulations are in good agreement with the analytical ones

ISPH modeling of Rayleigh–Taylor instability

This paper presents a Smoothed Particle Hydrodynamics (SPH) solution to a Rayleigh-Taylor Instability (RTI) problem in an incompressible viscous two-phase immiscible fluid with an interfacial tension. The evolution of the fluid-fluid interface is numerically investigated for four different density ratios. The simulation outcomes are compared with existing results in literature. Three stages of instability, namely the exponential growth rate, the formation of circular form at the crest of spike and the appearance of the final shape of instability, are discussed for different density ratios. It is shown that the numerical algorithm used in this work is capable of capturing the complete physics behind the RTI, such as interface evolution, growth rate and secondary instability accurately, and successfully

Very large dielectric response from ferroelectric nanocapacitor films due to collective surface and strain relaxation effects

Dependence of the dielectric response of ferroelectrics on defect types, particularly those with long range strain fields in confined geometries have been often mentioned, especially in interpreting experimental results in films. However, detailed discussions on the mechanisms with which defects alter properties, particularly in the presence of interfaces imposing certain boundary conditions, are seldom made. Here, we studied the thickness dependence of transition temperatures and dielectric response of Metal/BaTiO3/Metal ferroelectric nanocapacitor structures grown on SrTiO3 using a phenomenological approach accounting for the equations of electrostatics and semiconductors. Relaxation of the misfit strain via misfit dislocations amplify the surface effects in films below a critical thickness and favor electrical domains leading to very large dielectric responses in this regime. Thin film structures with relaxed misfit strain in this work are fully-depleted in the presence of moderate densities of impurities (~1025 m-3). This is due to the reduction of polarization amplitude parallel to the film normal and its mplications for near-micron thick films are discussed. Consequently, the misfit dislocation sites have nearly no free carrier localization, making the role of these sites on leakage currents highly questionable. Dielectric response of intrinsic thicker films (>40 nm) are mostly under the influence of strain relaxation only with minimal interface impact in the limit of ideal electrodes. Our results point out that control of the dislocation density can lead to non-conventional functionalities in ferroelectric thin film capacitors via electromechanical coupling of properties to structure and domain stabilization

A numerical investigation into the correction algorithms for SPH method in modeling violent free surface flows

A quantitative comparison of the usual and recent numerical treatments which are applied to the Smoothed Particle Hydrodynamics (SPH) method are presented together with a new free-surface treatment. A series of numerical treatments are studied to refine the numerical procedures of the SPH method particularly for violent flows with a free surface. Two dimensional dam-break and sway-sloshing problems in a tank are modeled by solving Euler's equation of motion utilizing weakly compressible SPH method (WCSPH). Initially, the dam-break benchmark problem is studied by adopting only conventional basic equations of SPH without any numerical remedy and then by considering numerical treatments of interest one after another. In the WCSPH method, the precise calculation of the densities of the particles is vital for the solution, accordingly a density correction algorithm is presented as a basic numerical treatment. Subsequently, Monaghan's (1994) [1] XSPH velocity variant algorithm, artificial particle displacement (APD) algorithm (Shaldoo et al., 2011) [2], and a hybrid combination of velocity updated XSPH (VXSPH) and APD algorithms are implemented separately, but all with the density correction algorithm as a default treatment. The effects of each of these treatments on the pressure and on the free surface profiles are analyzed by comparing our numerical findings with experimental and numerical results in the literature. After the detailed scrutiny on the dam-break problem, sway-sloshing problem is handled with the VXSPH+APD algorithm which has been noted to provide the most reliable and accurate results in the dam-break problem. For the sway-sloshing problem, the time histories of free surface elevations on the left side wall of the rectangular tank are compared with experimental and numerical results available in the literature. It was shown that the VXSPH+APD treatment significantly improves the accuracy of the numerical simulations for violent flows with a free surface and lead to the results which are in very good agreement with experimental and numerical findings of literature in terms of both the kinematic and the dynamic point of view

Politicization of the id; example Tunceli̇

Dersim coğrafyası sahip olduğu mekânsal koşullar ve kültürel özgünlüklerinden ötürü iktidarlarla arasında mesafeli bir ilişki kurmuş, bu durum Türk ulusalcılığın tesis edilmeye başlandığı 20. yüzyıılın başlarına kadar devam etmiştir. Dersim halklarının büyük bir çoğunluğunun Kürt/Zaza etnik kimliğine sahip olması, halkın anadolu aleviliğinin özgün örneklerinden olan kızılbaş alevileğe sahip olması ve Dersim’in geleneksel toplum yapısı Türk ulusalcılığı açısından bölgenin sorunlu bulunmasına sebebiyet vermiştir. Türk ulusalcılığın etnik anlamda Türklüğü merkeze alan üst/ulusal/tek kimlik, örtük bir biçimde sünni hanefi islamını içermesi, ulus devletin Dersim’e temas tarzını yoğunluğunu önemli ölçüde şekillendirmiş, coğrafyada yoğunluğuna çok rastlanılmayacak düzeyde siyasal, toplumsal ve militarist şiddetin vuku bulmasına sebebiyet vermiştir. Katliam, sürgün ve asimilasyon süreçleri refkelsif sonuçlar üretmiş, Kürt ulusalcılığı ve Kürt siyasal hareketinin bölgede ve Tunceli’de karşı poltik bir güç olarak yer alacağı vegüçlenebileceği geniş bir alan açmıştır. Siyasal şiddetin ve mücadelenin etnik, dinsel ve kültürel temelde vucut bulması kimliğin siyasal bir özne olarak merkeze alınmasına, siyasallaşmasına ve bağlantılı olarak kimlik temelli sorunların siyasal alanın söylem ve eylem pratiklerini dönüştürmesine sebebiyet vermiştir. Bu durum tabi bir sonuç olarak Tunceli’yi iki farklı siyasal gücün-bir açıdan milliyetçiliğin- mücadele alanına dönüştürmüştür. Tunceli kent merkezinde kimliğin siyasallaşma tarzını, kimlik temelli çatışmanın doğasını algılamak adına, kimlik, siysal tutum, hafıza ve siyasal iklim bağlamlarında gerçekleştirdiğimiz entelektüel arayış, iki yönlü kutuplaşmanın izini sürmemizi olanaklı kılmıştır. Farklı politik tutumlara sahip olan bireylerin kimliklerini tanımlama ve anlamlandırma biçimlerinden, yaşadıkları coğrafyayı adlandırma ve anlamlandırma biçimlerine, bireylerin kolektif hafızalarını inşa etme ve kurgulama biçimlerinden politik eyleyiclerin tavır, tutum, söylem pıratiklerinin şekillendirdiği siyasal iklimin etki tarzına kadar birçok gösterge kimlik ve kültür temelli çatışma ve kutuplaşmayı gösterir niteliktedir.Due to spatial conditions and cultural riginality owned Dersim geography has established that a distance Rapporto between the government, in this case Turkish nationalism that started to plant 20 until the beginning of the Yüzyııl etmiştir.dersim my people the majority of the Kurdish / ZaZa have the ethnic identity of the original sample of people Anatolian Alevism Kızılbaş be having my lesson alaevileg and traditional social structure gave rise to no problem in terms of Turkish nationalism. Turkish nationalism ethnic sense of Turkishness centered top / national / single identity, implicitly in the Sunni Hanafi the intensity of the style touch my class to the nation-state include the Islam has shaped significantly geography at levels not seen much on the intensity of the political, lead to the occurrence of social and militarist violence., shoot and assimilation processes have produced refkelsif results, Kurdish nationalism and Kurdish regions of political movement and a wide range açmıştır.siyasal violence will take place and be strengthened as a politics concerning force against Tunceli and fight etnisty, religious and cultural foundations in the body to find the identity of a political subject in the center of the forehead to, and politicization of identity-based discourse in the political sphere of action gave rise to problems linked and pıratik conversion. As a result of this case it has been subject to tunceliy into two different political power-struggle perspective natıon nationalism- field. Identity in Tunceli city center politicization style, identity-based in order to detect the nature of the conflict, identity, siysal attitude, intellectual quest we have made in memory and political climate context, two-way polarization to trace our possible kılmıştır.farkl define the identity of the individuals who have the political attitudes and way of interpretation of where they live geography naming and meaning formats, to build the kolektive memory of individuals and editing forms of politics concerning the actuator of the actuators of the attitude, attitude, tell pıratik of up to style influence the political climate has shaped many indicators identity and as cultural shows based conflicts and polarization