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نتیجه جستجو - قانون قدرت

تعداد مقالات یافته شده: 24
ردیف عنوان نوع
1 Buoyancy-driven convection in a horizontal porous layer saturated by a power-law fluid: The effect of an open boundary
همرفت ناشی از شناوری در یک لایه متخلخل افقی اشباع شده توسط یک مایع قدرت قانون: تأثیر یک مرز باز-2020
An infinitely wide horizontal porous layer saturated by a power-law fluid is heated from below by an imposed heat flux. The basic stationary state is characterised by a horizontal throughflow and a constant temperature gradient along the vertical direction. A linear stability analysis is performed by employing the method of normal modes. The eigenvalue problem obtained is solved by employing two different approaches: a hybrid analytical/numerical technique and a fully numerical technique. The critical values defining the threshold configurations for the onset of thermal convection are presented. These threshold values display a non monotonic dependence on the basic flow rate while they are monotonically increasing functions of the power-law index.
Keywords: Thermal convection | Porous medium | Power-law fluid | Linear stability analysis | Open boundary
مقاله انگلیسی
2 Augmentation and diminution of non-Boussinesq effects due to non-Newtonian power-law behavior in natural convection
افزایش و کاهش اثرات غیر Boussinesq به دلیل رفتار قدرت قانون غیر نیوتنی در همرفت طبیعی-2020
This study investigates the extent and significance of augmentation and diminution of non-Oberbeck– Boussinesq (NOB) effects due to power-law rheology in natural convection. The relative significance of each temperature dependent thermophysical property of a non-Newtonian power-law fluid was first evaluated using an order of magnitude analysis. The limiting criteria were derived for a class of fluids having an Arrhenius-type thermodependent consistency index, and a constant power-law index. Significant fluid property dependencies were identified, incorporated into the conservation equations, and solved numerically. The benchmark problem of natural convection around an isothermal vertical flat plate, immersed in a quiescent power-law fluid, was re-investigated from the viewpoint of NOB effects. It was found that power-law rheology significantly augmented or diminished the acceleration of flow caused by NOB effects. Compared to the Newtonian case, strong shear thinning behavior more than doubled the NOB acceleration of the flow field, and shear thickening inhibited the acceleration by nearly half. Numerical solutions facilitated the visualization of velocity and temperature distributions, and thus provided insights to the underlying physics. It is demonstrated that the cumulative effect of the power-law behavior and temperature dependence of properties is more than a mere superposition of the individual effects. Important contributions from the present work include modifications to the OB approximation’s limiting criteria applicable to power-law fluids, insights into the effect of temperature dependent properties on the flow field and consequent heat transfer, and their correspondence to the results of the order of magnitude analysis. The present investigation of the underlying physics of augmentation and diminution facilitate a better understanding for future studies of NOB effects combined with non-Newtonian behavior.
Keywords: Limiting criteria | Non-Oberbeck–Boussinesq | Order of magnitude analysis | Power-law fluid | Temperature dependent | Thermophysical properties
مقاله انگلیسی
3 Quantifying financial market dynamics: Scaling law in rank mobility of Chinese stock prices
کمییت پویایی بازار مالی: مقیاس بندی قانون در تحرک رتبه قیمت سهام چینی-2020
Rank mobility, which was designed to measure the average variation of relative rank positions with respect to any absolute variable over a given time period, can be used to explore how the memory of stock price ranking orders fades over time. We investigate the variations in rank order of the closing prices of stocks registered at the Shanghai A-share market over a long period of 16 years. And we find that rank mobility increases as a power law with increasing time scale, and eventually converges to a constant level. This power-law relationship can be observed not only over a long period of 16 years but also for each consecutive year, especially their power-law exponents are very close. The empirical evidence indicates a fundamental dynamics of Chinese stock price movements.
Keywords: Rank mobility | Stock price co-movement | Stock price dynamics | Firm-specific information | Power law
مقاله انگلیسی
4 Analysis of power law fluid-structure interaction in an open trapezoidal cavity
تجزیه و تحلیل تعامل قدرت ساختار سیال در قانون در حفره ذوزنقه باز-2020
The present paper investigates the mixed convection heat transfer of non-Newtonian fluid-structure interaction (FSI) inside an open trapezoidal cavity. The base of the cavity is fixed at constant temperature while the other walls are adiabatic. The flow passes over the open side of the cavity through a parallel-plate channel. An elastic fin is dangled from the top wall of the channel and stand facing the open cavity. The current model presents a two- dimensional incompressible laminar flow and unsteady-state conditions using the non-Newtonian power- law fluids. Numerical simulation is achieved using finite element method with arbitrary Lagrangian–Eulerian (ALE) scheme. The effects of Cauchy number, Reynolds number, Richardson number and the index of power law fluid are examined with ranges of (Ca = 10 − 20 –10 − 3 , Re = 100–300, Ri = 0.01–10 and n = 0.5–1.5). The results show that at Re = 300, Nusselt number of a stifffin is 2.6% and 7% higher than that of softer flexible fin for n = 0.5 and 1.5, respectively. For low Ri number, shear-thickening fluid manifests higher Nusselt number while for high Ri number, the shear-thinning fluid has the higher values. It is found also that the fluttering phenomenon of the fin takes place at the highest Ri and Re numbers with shear-thinning fluid and Newtonian fluid as well.
Keywords: Non-Newtonian fluid | Power law | FSI | Mixed convection | Trapezoidal cavity | Channel
مقاله انگلیسی
5 A novel representation of time-varying viscosity with power-law and comparative study
نمایش جدیدی از ویسکوزیته متغیر با زمان با قانون قدرت و مطالعه مقایسه ای-2020
Time-varying viscosity of viscoelastic materials has been found to induce complex rheology behaviors, which cannot be well characterized by the classical viscoelastic models. In this paper, different types of time-varying viscosity, namely, linearly varying viscosity, exponentially varying viscosity, and the proposed power-law viscosity are introduced with the applications to describing experimental data. Subsequently, these time-varying viscosities are embedded into the classical viscoelastic models. The relaxation and creep responses of the modified viscoelastic models are analytically derived and compared with the performance of the corresponding fractional models. The results indicate that the proposed power-law viscosity and the exponentially varying viscosity are capable of characterizing both thixotropy and rheopexy. The modified Maxwell model with power-law viscosity agrees well with the creep and relaxation responses of time-varying materials. It is also found that viscoelastic materials exhibiting thixotropy show faster rheological responses than the materials exhibiting rheopexy.
Keywords: Time-varying viscosity | Power-law viscoelastic model | Relaxation response | Creep response
مقاله انگلیسی
6 Beyond the particular case of circuits with geometrically distributed components for approximation of fractional order models: Application to a new class of model for power law type long memory behaviour modelling
فراتر از مورد خاص مدارهای با مؤلفه های توزیع شده هندسی برای تقریب مدلهای مرتبه کسری: کاربرد یک کلاس جدید از مدل برای نوع رفتار قدرت مدل سازی حافظه طولانی-2020
In the literature, fractional models are commonly approximated by transfer functions with a geometric distribution of poles and zeros, or equivalently, using electrical Foster or Cauer type networks with components whose values also meet geometric distributions. This paper first shows that this geometric distribution is only a particular distribution case and that many other distributions (an infinity) are in fact possible. From the networks obtained, a class of partial differential equations (heat equation with a spatially variable coefficient) is then deduced. This class of equations is thus another tool for power law type long memory behaviour modelling, that solves the drawback inherent in fractional heat equations that was proposed to model anomalous diffusion phenomena.
Keywords: Power law type long memory behaviours | Fractional models | Cauer networks | Foster networks | Heat equation | Poles and zeros geometric distributions
مقاله انگلیسی
7 A comparative analysis of flow features of Newtonian and power law material: A New configuration
تجزیه و تحلیل مقایسه ای از ویژگی های جریان مواد نیوتن و قانون قدرت: پیکربندی جدید-2020
In recent years, material analysis of fluids has generated prodigious interest of researchersdue to their effective role in interdisciplinary sciences. In view of its importance, the presentcommunication is devoted to analyze the flow of power law fluid representing the fea-tures of shear thinning, shear thickening and Newtonian materials. Constitutive equationsexpressed in the form of tensorial representations depicting power law relation betweenviscosity and shear rate. The whole mathematical model is solved computationally via offinite element method by using stable P2− P1finite element pair. A highly refined hybridmesh is obliged for the accurate computation of results. Material properties of power lawfluid are disclosed in physical configuration renowned as channel driven cavity combiningvarious benchmark problems like cavity flow, forward and backward facing steps and chan-nel flow. Impact of material parameters on pertinent profiles is disclosed through graphs.Verification of computed results is done by comparing the velocity, viscosity, pressure fieldsfor power law fluid with the Newtonian case.
Keywords: Finite element method | Power-law fluid | Channel driven cavity | Shear thinning and shear thickening
مقاله انگلیسی
8 CFD analysis for characterization of non-linear power law material in a channel driven cavity with a square cylinder by measuring variation in drag and lift forces
تجزیه و تحلیل CFD برای توصیف مواد قانون قدرت غیر خطی در حفره کانال هدایت شده با یک سیلندر مربع با اندازه گیری تغییر در نیروهای درگ و بالابر-2020
Current communication is manifested to investigate flowing features of power law mate-rial in a newly proposed physical configuration namely the channel driven cavity. Sincepower law fluid discloses the dynamical features of shear thinning, shear thickening andNewtonian materials so in present communication it is considered for depiction of flowattributes. To achieve the desired outcomes from the work, a unit length cavity is placedbelow the channel. The flow is induced with parabolic inlet velocity and a Neumann condi-tion is applied at the outlet, while no slip condition is set at all other boundaries. A squarecylinder is placed in the channel with varying positions giving rise to three computationalgrids named as G1, G2and G3.Mathematical modelling is constructed by obliging funda-mental conservation and rheological laws for power law fluid. Since the representativeequations are complex in nature so an efficient computational procedure based on finiteelement method (FEM) is executed. A hybrid computational grid is generated at coarse leveland then further refinement is done to improve the accuracy of the solution. The solution isapproximated by adopting P2− P1element based on second and first order polynomial shapefunctions. Graphical trends against involved parametric variables are adorned. In additionfor more physical insight of problem velocity and pressure plots and line graphs are added.Furthermore, the hydrodynamical benchmark quantities like pressure drop, drag and liftcoefficients are evaluated in tabular form around the outer surface of obstacle.
Keywords:Finite element method | Power law materia | lDrag and lift coefficients| Channel-driven cavity
مقاله انگلیسی
9 Optical solitons and other solutions to the dual-mode nonlinear Schrödinger equation with Kerr law and dual power law nonlinearities
Solitons نوری و راه حل های دیگر برای معادله Schrödinger دو حالت غیرخطی با قانون Kerr و غیرخطی های قانون قدرت دوگانه-2020
In this article, we apply four insightful integration algorithms, namely, the tanh-coth method, the unified Riccati equation method, the modified simple equation method and the new extended auxiliary equation method for constructing new optical soliton solutions and other solutions to the dual-mode nonlinear Schrödinger equation with Kerr law and dual power law nonlinearities related to the optics. Many families of Jacobi elliptic solutions, dark, bright, singular soliton solutions and other solutions have been found.
Keywords: The tanh-coth method | The unified Riccati equation method | The modified simple equation method | The new extended auxiliary equation method | Dual-mode nonlinear Schrödingers equation | Optical soliton solutions
مقاله انگلیسی
10 Boundary optimal control for antiplane contact problems with power-law friction
کنترل بهینه مرزی برای مشکلات تماس antiplane با اصطکاک قانون قدرت -2020
We consider a contact model with power-law friction in the antiplane context. Our study focuses on the boundary optimal control, paying special attention to optimality conditions and computational methods. Depending on the exponent of the power-law friction, we are able to deduce an optimality condition for the original problem or for a regularized version of it. Furthermore, we introduce and analyze a computational technique based on linearization, saddle point theory and a fixed point method. For a slightly modified optimal control problem, some numerical experiments are presented.
Keywords: Nonlinear boundary value problem | Antiplane contact model | Power-law friction | Optimal control | Optimality conditions | Fixed point | Approximation
مقاله انگلیسی
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