Comparative Study on Effects of Thermal Gradient Direction on Heat Exchange between a Pure Fluid and a Nanofluid: Employing Finite Volume Method

This work aims to determine how the temperature gradient orientation affects the heat exchange between two superposed fluid layers separated by zero wall thickness. The finite volume method (FVM) has been developed to solve the governing equations of both fluid layers. To achieve the coupling between the two layers, the heat flow continuity with the no-slip condition at the interface was adopted. The lower part of the space is filled with a nanofluid while the upper part is filled with a pure fluid layer. We have explored two cases of temperature gradient orientation: parallel gradient to gravity forces of our system and perpendicular gradient to gravity forces. We took a set of parameters, Ri and ϕ, to see their influence on the thermal and hydrodynamic fields as well as the heat exchange rate between the two layers. The main applications of this study related to biological systems such as the cytoplasm and the nucleoplasm are phase-separated solutions, which can be useful as models for membranelles organelles and can serve as a cooling system application using heat exchange. The Richardson number and the volume of nanosolid particles have a big impact on the rate of change of heat transmission. When a thermal gradient is perpendicular to gravity forces, total heat transmission improves with increasing solid volume percentage, but when the thermal gradient is parallel to gravity forces, overall heat transfer decreases significantly.

Simulation of Multi-Gas Jet Flows by Use of Quasi Gas Dynamic Equation System

In the present paper, we use the quasi gas dynamic (QGD) model together with a finite volume method for the simulation of a gas jet inflowing region filled with another gas in the presence of gravity forces. A flow picture for such flow strongly depends on the gases density ratio. Numerical simulations are held for a region filled with air under atmospheric pressure. Three variants of inflowing gas are considered: methane (light gas), butane (heavy gas) and helium (extremely light gas). A difference between flow pictures for these test cases is demonstrated. Results obtained with the presence of wind in the air are also compared. Grid convergence is established by use of different spatial meshes. Here, the the QGD model demonstrated good efficiency in modeling multi-gas jet flows. The calculations were also used for the adjustment of the numerical method parameters.

The Effect of SPIO Nanoparticles Size on Transduction of PEGylated Lentiviral Vector

Gene editing has revealed many promising opportunities for the treatment of severe diseases including cancers and autoimmunes. There are two main routes for gene delivery: viral and non-viral. Recent research shows viral methods are very close to clinical trials. Nevertheless, there are a couple of obstacles to remove such as difficulty in virus concentration, low efficiency of transduction, and being time-consuming. In this work, by employing magnetic nanoparticles (NP) we tried to solve these problems. Conjugating these nanoparticles to viruses by polyethylene glycol (PEG) can increase sedimentation of viruses due to magnetic and gravity forces even without ultracentrifuge. Moreover, this magnetic force can guide viruses toward cells and tremendously facilitate the transduction process. Nanoparticle size has significant effects and should be considered for this application. As shown, average size nanoparticles revealed the best performance especially in combination with salting-out precipitation and increased transduction efficiency more than 20-fold.

Inertial effects in dusty Rayleigh–Taylor turbulence

We investigate the dynamics of a dilute suspension of small, heavy particles superposed on a reservoir of still, pure fluid. The study is performed by means of numerical simulations of the Saffman model for a dilute particle suspension (Saffman, J. Fluid Mech., vol. 13, issue 1, 1962, pp. 120–128). In the presence of gravity forces, the interface between the two phases is unstable and evolves in a turbulent mixing layer which broadens in time. In the case of negligible particle inertia, the particle-laden phase behaves as a denser fluid, and the dynamics of the system recovers to that of the incompressible Rayleigh–Taylor set-up. Conversely, particles with large inertia affect the evolution of turbulent flow, delaying the development of turbulent mixing and breaking the up–down symmetry within the mixing layer. The inertial dynamics also leads to particle clustering, characterised by regions with higher particle density than the initial uniform density, and by the increase of the local Atwood number.

Operator-Based Linearization Approach for Modeling of Multiphase Flow with Buoyancy and Capillarity

Summary Numerical simulation of coupled multiphase multicomponent flow and transport in porous media is a crucial tool for understanding and forecasting of complex industrial applications related to the subsurface. The discretized governing equations are highly nonlinear and usually need to be solved with Newton’s method, which corresponds with high computational cost and complexity. With the presence of capillary and gravity forces, the nonlinearity of the problem is amplified even further, which usually leads to a higher numerical cost. A recently proposed operator-based linearization (OBL) approach effectively improves the performance of complex physical modeling by transforming the discretized nonlinear conservation equations into a quasilinear form according to state-dependent operators. These operators are approximated by means of a discrete representation on a uniform mesh in physical parameter space. Continuous representation is achieved through the multilinear interpolation. This approach provides a unique framework for the multifidelity representation of physics in general-purpose simulation. The applicability of the OBL approach was demonstrated for various energy subsurface applications with multiphase flow of mass and heat in the presence of buoyancy and diffusive forces. In this work, the OBL approach is extended for multiphase multicomponent systems with capillarity. Through the comparisons with a legacy commercial simulator using a set of benchmark tests, we demonstrate that the extended OBL scheme significantly improves the computational efficiency with the controlled accuracy of approximation and converges to the results of the conventional continuous approach with an increased resolution of parametrization.

Simulation of several flying situations of paragliders

Paragliding is an adventure and fascinating sport of flying paragliders. Paragliders can be launched by running from a slope or by a winch force from towing vehicles, using gravity forces as the motor for the motion of flying. This motion is governed by the gravity forces as well as time-varying aerodynamic ones which depend on the states of the motion of paraglider at each instant of time. There are few published articles considering mechanical problems of paragliders in their various flying situations. This article represents the mathematical modeling and simulation of several common flying situations of a paraglider through establishing and solving the governing differential equations in state-space. Those flying situations include the ones with constant headwind/tailwind with or without constant upwind; the ones with different scenario for the variations of headwind and tailwind combined with the upwind; the ones with varying pilot mass; and the ones whose several parameters are in the form of interval quantities. The simulations were conducted using a powerful Julia toolkit called DifferentialEquations.jl. The obtained results in each situation are discussed, and some recommendations are presented. Keywords: paraglider; simulation; modeling; state-space; ordinary differential equations; Julia; DifferentialEquations.jl

System of electron-proton. Movement, rotation, pulsation and Gravity Forces

The new Field Theory consist two new Axioms and eight new Laws. It has been proposed and developed in previous reports by the same author. This report uses two axioms and six laws only. According to the first axiom (Axiom1), the author replaces uniform motion in a closed circle with non-uniform motion in an open vortex. According to the second axiom (Axiom2), it exists a pairs of vortices that are mutually orthogonal or they work in a system of resonance. The most probable of all of variants is the following pair: accelerating vortex from the center outwards connected with a decelerating vortex from the periphery inwards. This case is a model of the connected proton-electron pair. In this report the properties of a system only of linked electrons and protons are studied. It is known that the Electromagnetic Field propagates at a constant speed and the waves are only transverse. According to the new Axioms and Laws in the electron-proton system, the internal connections are of variable speed and the waves are not only transverse but and longitudinal. It appears that the interactions between the proton and the electron are not Electromagnetic. They include cross vortex with variable velocity and longitudinal vortex with variable velocity as well. From previous developments it is clear that the electron is not a concentric open vortex but an eccentric open vortex, centered in the second quadrant. And the proton is not a concentric open vortex but an eccentric open vortex, centered in the first quadrant. This is the reason for the formation of eccentricity vectors that decompose along the x and y axes. Because the eccentricity of the electron is greater than the eccentricity of the proton then the component along they axis rotates the electron around the proton (in orbit). And besides, since the decelerating vortex of the electron emits elementary decelerating vortices (Law 5) inward which are bent in the direction of the decelerating velocity, the electron will rotate parasitically and slowly around its own axis (in spin). The electron and proton are repelled gravitationally by a transverse component and are attracted gravitationally by a longitudinal component which are with variable speed. The existence of feedback between the electron and the proton (Law 7 and Law 8) explains the reason for the presence of elementary cross vortices. When they are emitted outward - are called “free energy”. And because they are invisible -are called and “black matter” as well.

Institutions, Culture and Foreign Direct Investment in Transition Economies: Does Culture Matter and Why?

The aim of this research is to analyse the importance of cultural and institutional determinants in attracting FDI to transition countries. We rely on gravity econometric framework and examine the impact of cultural and institutional factors on FDI using bilateral FDI flows between home (i.e. major trading partners) and eight transition economies in the period 2000–2018. We study this relationship in an integrated framework considering principal gravity forces, traditional FDI determinants, policy and institutional factors. We provide strong and robust evidence that cultural factors, depicted in Hofmann cultural indices, influence MNCs’ locational decisions. Other things held constant, specific cultural features seem more important than formal institutions, which seems at odds with standard neoclassical propositions, and shed some new light on the way we understand international business transactions.

What Is Temperature? Modern Outlook on the Concept of Temperature

The meaning and evolution of the notion of “temperature” (which is a key concept for the condensed and gaseous matter theories) are addressed from different points of view. The concept of temperature has turned out to be much more fundamental than conventionally thought. In particular, the temperature may be introduced for systems built of a “small” number of particles and particles at rest. The Kelvin temperature scale may be introduced into quantum and relativistic physics due to the fact that the efficiency of the quantum and relativistic Carnot cycles coincides with that of the classical one. The relation of temperature with the metrics of the configurational space describing the behavior of systems built from non-interacting particles is demonstrated. The role of temperature in constituting inertia and gravity forces treated as entropy forces is addressed. The Landauer principle asserts that the temperature of a system is the only physical value defining the energy cost of the isothermal erasure of a single bit of information. The fundamental role of the temperature of the cosmic microwave background in modern cosmology is discussed. The range of problems and controversies related to the negative absolute temperature is treated.