Entropy generation minimization (EGM) in magneto peristalsis with variable properties

Irreversibility effects in peristaltic transport of hybrid nanomaterial in the presence of heat absorption

The nano heat transport has gained much significance in recent era. The micro-level devices are enganged succssfully in diverse fields like electronics, biomedical, navel structures, manufacturing, transportation, and automotive industries in order to improve the heat transfer for cooling and heating. Owing to this fact, the current article illustrates the features of irreversibility and thermal jump in peristaltic transport of hybrid nanoliquid. Here, water is used as base liquid while nanoparticles include polystyrene and graphene oxide. The flow is carried out in a non-uniform channel where the walls of channel flexible nature. Additionally, magnetic field impacts on flow and Joule heating analysis are examined. The aspect featuring heat absorption is introduced. Nanoparticle's shapes effect is also incorporated in flow analysis. Under the consideration of small Rynold number and long wavelength, the relevent equations are reduced by implementing non-dimensional variables. Involved pertinent parameters influence the peristaltic flow characteristics are displayed graphically and discussed concisely. The result indicates that temperature curves are dominant for pure water as compared to P/water nanofluid and P-GO/water hybrid nanofluid. Moreover, the convergent channel shows least entropy effects and extreme effects are noted for divergent case whereas uniform channel stays behind the divergent one.

Modeling and interpretation of peristaltic transport in single wall carbon nanotube flow with entropy optimization and Newtonian heating

Due to some special characteristics like the effective thermal conductivities, appropriate mechanical features, and superior electrical properties, carbon nanostructures have been known as the proper materials to reach the desired characteristics of fluids. In the recent past fluid flows through peristaltic mechanism subject to carbon nanotubes are utilized to handle the overcome of industrial and physiological materials thermal properties. Due to rich thermal characteristics nanotubes are used into basic industrial materials to improve the required ability of thermal properties of these industrial materials. Thus various kinds of nanoparticles e.g. aluminum, copper, zinc oxides and carbon nanotubes are significantly utilized to increase the thermal abilities of base liquids. Because of the several significant special qualities such as improved thermal conductivities, applicable mechanical structures, and rich electrical properties, CNTs have been acknowledged as the accurate tools to reach the wanted features of fluids, due to such abilities CNTs are high demanding research topic in all domains. Keeping such efficiencies of CNTs in notice, this analysis is prepared for peristalsis of carbon nanotubes through non-uniform asymmetric channel. Flow mechanism is modeled in view of conservation principles under desired assumptions likely porous medium, non-linear mixed convection, heat generation absorption and Newtonian heating. Rate of total entropy is evaluated by using thermodynamics second law. Lubrication approach utilized here to attain the simplified form of the complex flow expressions. The pressure gradient, velocity along axial direction, temperature, effective heat transfer rate and entropy expressions subject to boundary conditions are evaluated numerically via built-in-Shooting procedure. Furthermore these numerical results are used to sketch the variations of all the above mentioned quantities against the pertinent parameters of interest. According to physical discussion temperature reduces for heat absorption case and enhances for heat generation case. Impact of Prandtl number on entropy indicates that entropy is minimum due to less fluid friction (i.e. Prandtl number less than 1).

Variable characteristics of viscosity and thermal conductivity in peristalsis of magneto-Carreau nanoliquid with heat transfer irreversibilities

BACKGROUND

Peristaltic is a basic way of fluid transportation in physiology, engineering and nuclear industry. Importance of peristalsis is due to its contraction and compulsion property of symmetric and asymmetric type channel walls. Another beauty of this mechanism is that the channel walls propagates and push the material along the tube/conduit channel walls. This mechanism shows its presence in physiology while food particles are transferred through esophagus and stomach, urine through intestines, spermatoza transportation in reproductive tract. In industry it is found in roller and finger pumps, drug delivery and various nuclear materials e.g. toxic, corrosive, noxious etc. Magnetic field in peristalsis is found helpful in treatment of various treatments using magnets. Actually earth and human body as a whole comprises of magnetic and electric fields. The medical specialists found that unbalances of electromagnetic field in human body is the reason for emotional and physical disturbance. In addition it has significant and potential utilizations in modification of medical, industrial and chemical, procedures for example MRI, evaporation, convection, thermoregulation, MHD throttles, and in various types of tumor treatments. Entropy production work out irreversibility in complex systems which are frequently encountered in industrial mechanisms. In view of that, this methodology is effectually implemented in distinct technological applications covering porous media, propulsion ducts, electronic cooling, turbo-machinery and combustion.

METHOD

Modelled flow mechanism is nonlinear and coupled due to considered assumptions (i.e. nanofluid, nonlinear porous channel, mixed convection, variable viscosity and thermal conductivity, activation energy and chemical reaction). Such nonlinear and coupled system is difficult to tackle analytically. Thus to obtain the solution we employed RK algorithm for numerical simulations.

RESULTS

Stronger magnetic parameter shows resistive characteristics to the flow field. Nonlinear Darcy medium assists the fluid motion at channel center and resits at walls vicinity. Variable characteristics of thermal conductivity moderate the soak or disperse up heat ability which corresponds to temperature reduction. Thermal slip quantity increase the temperature whereas concentration slip deduct the concentration of Carreau nanomaterial. Entropy and Bejan number shows maximum response for higher dissipation estimations. Brownian and thermopherotic motions aspects has reverse impact on nanomaterial concentration.

CONCLUSION

Entropy and Bejan number deduces for higher variable thermal conductivity values. Carreau material variable enhance the entropy of the system as a whole.