Thermal magnetic nanosuspension convection in narrow channels

Abstract

The results of comparative experiments on the convection of magnetic fluids and molecular binary fluid mixtures in connected vertical channels heated from below are discussed. In both media, near the equilibrium stability threshold, flows in the form of specific swing oscillations are observed. The results of the experiment form a basis for a three-component model for magnetic fluid convection which takes into account the thermodiffusion separation of the dispersion medium components and the weak sedimentation of magnetic particles. The results of numerical simulation and experiment are compared.The specific low-frequency convective ferrofluid oscillations in connected vertical channels, described in [1], surprisingly turned out to be qualitatively similar to the binary mixture oscillations. In the medias of both types, near the equilibrium stability threshold, periodic changes in the channel flow direction were observed. The nature of the convective oscillations of molecular binary mixtures was established, the theory of the phenomenon was developed, numerical and analytical calculations were carried out, and the results were described in a series of papers [2][3][4]. It was revealed that in these oscillations the determining role is played by the positive thermodiffusion of a heavy molecular admixture.In order to understand the nature of the convective oscillations in ferrofluids, novel comparative experiments were carried out with ferrofluids and aqueous sodium sulfate solutions. The experimental results obtained make a basis for formulating equations that describe the convection of the magnetic fluid as a three-component fluid consisting of a binary carrier filled with magnetic particles.

Stability of equilibrium and convective regimes of nanosuspension on the base of binary molecular medium

“…онные коэффициенты плотности, описывающие зависимость плотности элемента жидкости от концентрации тяжелого компонента жидкости и наночастиц. Полная система уравнений тепловой конвекции в безразмерной форме, с учетом термодиффузии и седиментации в безразмерных переменных принимает вид [11] ()…”

“…В последнее время описанию тепло-и массопереноса в жидких многокомпонентных средах уделяется огромное внимание как в отечественной, так и зарубежной научной литературе [4][5][6][7][8][9][10][11][12][13][14]. Актуальность тематики связана с многочисленными приложениями в самых разных отраслях промышленности и в первую очередь химической [9].…”

Gravitational convection of magnetic colloid in a horizontal layer

“…Comparative experiments on generation of oscillations in a convective loop of magnetic colloid and molecular mixture used as a carrier fluid in the colloid were performed in work [13]. In both cases hard excitation of umklapp-assisted oscillations (oscillations with the change of direction of the flow in the loop) was observed.…”