Modelling of Applied Magnetic Field and Thermal Radiations Due to the Stretching of Cylinder

In this study, a numerical approach was adopted in order to explore the analysis of magneto fluid in the presence of thermal radiation combined with mixed convective and slip conditions. Using the similarity transformation, the axisymmetric three-dimensional boundary layer equations were reduced to a self-similar form. The shooting technique, combined with the Range–Kutta–Fehlberg method, was used to solve the resulting coupled nonlinear momentum and heat transfer equations numerically. When physically interpreting the data, some important observations were made. The novelty of the present study lies in finding help to control the rate of heat transfer and fluid velocity in any industrial manufacturing processes (such as the cooling of metallic plates). The numerical results revealed that the Nusselt number decrease for larger Prandtl number, curvature, and convective parameters. At the same time, the skin friction coefficient was enhanced with an increase in both slip velocity and convective parameter. The effect of emerging physical parameters on velocity and temperature profiles for a nonlinear stretching cylinder has been thoroughly studied and analyzed using plotted graphs and tables.

The importance of turbulent ocean-sea ice nutrient exchanges for simulation of ice algal biomass and production with CICE6.1 and Icepack 1.2

Different sea-ice models apply unique approaches in the computation of nutrient diffusion between the ocean and the ice bottom, which are generally decoupled from the calculation of turbulent momentum and heat flux. Often, a simple molecular diffusion formulation is used. We argue that nutrient transfer from the ocean to sea ice should be as consistent as possible with momentum and heat transfer, since all these fluxes respond to varying forcing in a similar fashion. We hypothesize that biogeochemical models which do not consider such turbulent nutrient exchanges between the ocean and the sea-ice underestimate bottom-ice algal production. The Los Alamos Sea Ice Model (CICE + Icepack) was used to test this hypothesis by comparing simulations with molecular and turbulent diffusion of nutrients into the bottom of sea ice, implemented in a way that is consistent with turbulent momentum and heat exchanges. Simulation results support the hypothesis, showing a significant enhancement of ice algal production and biomass when nutrient limitation was relieved by bottom-ice turbulent exchange. Our results emphasize the potentially critical role of turbulent exchanges to sea ice algal blooms, and the importance of thus properly representing them in biogeochemical models. The relevance of this becomes even more apparent considering ongoing trends in the Arctic Ocean, with a predictable shift from light to nutrient limited growth of ice algae earlier in the spring, as the sea ice becomes more fractured and thinner with a larger fraction of young ice with thin snow cover.

Modeling of Intensified Heat Exchangers with Different Fluid Viscosities

Equations are derived for mean friction and heat transfer coefficients to solve problems of updating industrial plants for getting oil fractions based on application of approximate method of modeling momentum and heat transfer in heat exchangers with surface intensifiers. The Dyssler and Van-Driest turbulent boundary-layer model is used for the turbulent viscosity function for a flat smooth wall. An equation for the Stanton number is written using Chilton-Colborne hydrodynamic analogy and agreement with the known analogy is shown. Identical local properties of turbulent motion in a boundary layer on a plate and in a near-wall layer of a tube and the conservative properties of the laws of friction and heat transfer to turbulences, which are taken account of parametrically, are used for modeling momentum and heat transfer in channels with surface intensifiers. An equation for mean tangential stress in channels with intensifiers and, further, an equation for the Nusselt number is derived using a dissipative model. The results of calculations and comparison with the known experimental investigations are given for tubes with surface wire inserts, with spiral finning and rectangular projections for transformer oil at Reynolds numbers 200 < Re <2000. Thus, the adequacy of the developed mathematical model is proved in a wide range of operating and design parameters and thermophysical properties of fluids and gases. Further, the hydraulic resistance of the channel is the key experimental information about the object of modeling. Examples of use of mathematical model for designing and commissioning heat exchangers in petroleum fuels fractionating plants at industrial enterprises in the Russian Federation and abroad are given.