A lattice Boltzmann study of particle settling in a fluctuating multicomponent fluid under confinement

We present mesoscale numerical simulations based on the coupling of the fluctuating lattice Boltzmann method for multicomponent systems with a wetted finite-size particle model. This newly coupled methodologies are used to study the motion of a spherical particle driven by a constant body force in a confined channel with a fixed square cross section. The channel is filled with a mixture of two liquids under the effect of thermal fluctuations. After some validations steps in the absence of fluctuations, we study the fluctuations in the particle’s velocity at changing thermal energy, applied force, particle size, and particle wettability. The importance of fluctuations with respect to the mean settling velocity is quantitatively assessed, especially in comparison with unconfined situations. Results show that the expected effects of confinement are very well captured by the numerical simulations, wherein the confinement strongly enhances the importance of velocity fluctuations, which can be one order of magnitude larger than what expected in unconfined domains. The observed findings underscore the versatility of the proposed methodology in highlighting the effects of confinement on the motion of particles in the presence of thermal fluctuations.

Fluid Mixing Nonequilibrium Processes in Industrial Piping Flows

The flow of a multicomponent fluid through a pipeline system of arbitrary configuration is considered. The problem consists in determining the component composition of the fluid for each pipeline of the system based on the values of the concentration of the components throughout the entire set of measuring points, provided that there are no phase transitions. To solve the problem, mathematical models have been developed that, in principle, are suitable for pipeline systems of various functional purposes, the presentation is concretized and carried out in relation to gas transmission systems. The models are stochastic in nature due to measurement errors, which are considered random variables. The solution of the problem is reduced to the optimization of a quadratic function with constraints in the form of equalities and inequalities. The considered mixing processes do not depend on the regime parameters of the fluid flow. The processes are irreversible and non-equilibrium. A criterion is introduced that characterizes the degree of closeness of a multicomponent mixture to an equilibrium state. The criterion is analogous to entropy in thermodynamic processes. A numerical example of calculating the distribution of a three-component mixture is given. The example illustrates the feasibility of the proposed computational procedures and gives an idea of the distribution of the component composition and the change in «entropy» along the directions of pumping of the gas supply system.

PARALLEL ALGORITHM ON CUDA FOR SOLVING MULTIPHASE, MULTICOMPONENT FLUID FILTRATION PROBLEMS IN POROUS MEDIA

The paper discusses the implementation of alternating direction implicit parallel algorithm with CUDA technology to solve the problems of multiphase filtration of a multicomponent fluid in porous media. To solve the tridiagonal equations systems of alternating direction implicit method, cyclic and parallel cyclic reduction methods were used. The results of the study showed that the implementation of cyclic and parallel cyclic reduction algorithms on modern GPUs is much more efficient than on CPUs.

Electrical method for intelligent cooling liquid control system

The ability to determine and control the normalized concentrations has been established using the experimentally obtained dependencies of the active and reactive constituents of conductivity in the wide frequency range of the electromagnetic field on the composition of the multicomponent fluid and the impurity concentrations. For high-aqueous substances dissolved in water (cooling liquids), a method for controlling the qualitative and quantitative composition is developed. It is based on the comparison of the measured and experimentally established active conductivity component and the comparison of the corresponding dependencies in the frequency field of the reactive component of conductivity. The developed electric method allows quantitative and qualitative estimation of the composition of the coolant on the contents of controlled components in the short time (up to 2 seconds) in a non-laboratory environment and to ensure uninterrupted operation of the equipment.