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Results of experimental studies and numerical modeling of high strain rate of aluminum alloy AK4-1 (analog AU2GN) have been presented. Using Split Hopkinson Pressure Bar (SHPB) method stress-strain curves under compression and tension have been obtained. On the basement of these results appropriate parameters of some constitutive equations have been calculated. Strength and deformation material failure properties, dynamic crack resistance, dynamic friction factor for material pair aluminum-titanium have been obtained by carrying out of modificated SHPB tests. A verification of the constitutive equations has been realized by dynamic indentation method and modified Taylor test.

A hydro-dynamic thermal fully developed forced convective heat transfer analysis of magneto-hydrodynamics fluid flow through an annular sector duct is presented in this paper. Two types of thermal boundary conditions i.e., axially uniform heat flux along with peripherally uniform temperature (known as H1-condition) and, axially and peripherally uniform temperature (known as T condition), have been considered to carry out the thermal analysis of fluid. The velocity components along r and $\theta$ direction are transformed into algebraic form by using power law discretized scheme, whereas cross-sectional pressure $P(r,\theta )$ is estimated with the help of well know technique $SIMPLER$. The governing partial differential equations are solved by numerically with the help of $MATLAB$ code. Furthermore, simulated results have been compared with the existing results of literature to validate the results. From the results, it is noted that hydro-dynamically and thermally impacts relate directly by increasing the Hartman number, (M). It is further reported that the effect of magnetic field becomes insignificant for the higher number of fins, N. The findings of the present analysis will be applicable in various types of thermal systems.

A three-dimensional compressible numerical model of micro-channel is established with consideration of the effect of velocity slip near walls. Meanwhile the gas viscosity is modified based on the Knudsen number using Veijola's model. The model is proved to be credible by comparing with analytical data. A new non-dimensional parameter relative slip length L_s/D_h is found to be very useful for describing friction characteristic for compressible flow with slip in micro-scale. The correlation for fRe with this new non-dimensional parameter L_s/D_h is suggested.

The importance of Methanol can be guessed from its usage as in the preparation of methyl tertiary butyl ether (MTBE) fuel, ascetic acid, formaldehyde, metabolize food, biodiesel, pharmaceutical ingredients and products, energy related applications and many more. In this research work, we numerically analyze the impact of temperature-dependent viscosity on flow and heat transfer of Methanol Iron oxide, CH₃OH–Fe₃O₄ nanofluid through annular sector duct. The effects of pertinent parameters corresponding to temperature-dependent viscosity, m, Fe₃O₄ nanoparticles’ contribution, n and geometrical configuration (i.e. $\widehat{R}$ and N), are revealed graphically by velocity contours, isotherms, velocity and temperature profiles, and discussed physically. Both parameters m and n suppress the velocity and temperature profiles by increasing the friction factor $f\mathrm{\text{Re}}$ and average Nusselt number $\mathrm{\text{Nu}}$. Same impacts of m and n have been observed for all values of $\widehat{R}$ and N.

An experimental study on pressure drop and heat transfer in single-phase was carried out using 10 types of internally helical-grooved and smooth small-diameter tubes with an outside diameter of 4 mm. The results are listed below: (1) In the turbulent flow region, fin height had the greatest effect, helix angle had only a minor effect, and the number of grooves had almost no effect upon the pressure drop versus the mass flow rate of the 4-mm grooved small-diameter tubes. In the laminar flow region, except for fin height, the shapes of the internal grooves had scarcely any effect upon pressure drop. (2) In the turbulent flow region, the heat transfer coefficients of the 4-mm grooved small-diameter tubes were greatly affected by fin height. The heat transfer coefficients became the maximum when a helix angle was near 15°, and there is a different tendency in the experiments of the pressure drop. On the other hand, there is almost no effect of the number of grooves. In the laminar flow region, there were no large differences in the heat transfer coefficients between the internally helical-grooved tubes and smooth small-diameter tube. (3) New empirical correlations for the friction factor and heat transfer coefficient in the laminar and turbulent flow regions were developed based on the experimental values. (4) The performance assessment in consideration of both heat transfer and pressure drop was indicated by using Colburn's analogy.

Thermal and hydraulic performances of various geometric shapes of a microchannel heat sink were evaluated numerically using Navier–Stokes equations. A heat sink comprised of a $1\times 1$cm² silicon wafer was investigated with water as the cooling fluid. The performances of seven microchannel shapes were compared at the same microchannel hydraulic diameter and the same average height of the bottom silicon substrate. The thermal resistance, friction coefficient, and Nusselt number were calculated for a Reynolds number range of 50 to 500. The results show that an inverse trapezoidal shape gives the lowest thermal resistance for a Reynolds number up to 300. The values of $f$Re are almost similar for all the shapes because of the constant hydraulic diameter.

Accurate prediction of the friction factor and consequently the pressure drop of two-phase flow in small channels is still an issue. Many correlations exist for the determination of the viscosity and the friction factor that appear in the frictional pressure drop and their combination often determined the degree of disagreements between the experimental data and predicted outcomes. Demands for environmentally friendly refrigerants have further posed a challenge to find compatible alternatives with as good a performance as the current coolants. Despite the many available correlations developed to date, many more are studied in effort to reduce the discrepancies. This paper presents the outcomes of a study comparing the optimized conditions when three different viscosity equations are paired with eight different friction factor correlations to minimize the frictional pressure drop. The approach used multi-objective genetic algorithm (MOGA) to assist in selecting the best pairing. Comparison is then completed with available experimental data. The study showed that the Blasius friction factor paired with the Dukler viscosity produced the least percentage difference for R22, while when paired with the McAdams viscosity produced a lower difference for R290, an environmentally friendly refrigerant being considered to replace R22.

The use of solar air heaters (SAH), which convert solar energy into heat energy, is one of the most efficient methods currently available for capturing the energy of the sun. However, because SAH have lower thermal efficiency, researchers have been concentrating on developing methods to modify the flow field to artificially boost thermal performance. In this work, a numerical investigation that focuses on a SAH that has been deliberately roughened using broken arc ribs is presented. This numerical analysis aims to determine the impact of incorporating broken arc ribs compared to smooth ones and how various roughness factors affect the friction factor and Nusselt number (Nu). The RNG k-$𝜀$ turbulence model was used for the simulation. To solve the continuity, momentum, and energy equations, version R19.2 of Ansys FLUENT software was used. The results of the CFD study show that the average Nusselt number increases if there is a greater relative roughness pitch, and it achieves its highest value once relative roughness pitch ($p/e)=12$. The friction factor, on the other side, decreases as the Reynolds number (Re) increases, reaching its lowest value when $p/e=12$ and $\mathrm{\text{Re}}=18,000$. Maximum value of the thermohydraulic performance factor is observed to be 1.92 when applied to the geometry that corresponds to relative roughness height ($e/D)=0.037$, ($p/e)=12$, and $\mathrm{\text{Re}}=6000$.

This chapter deals with the calibration of a new simplified experimental method to evaluate absolute roughness of vegetated channels. The method is based on boundary layer measurements in a short channel rather than on uniform flow measurements, as usual. The proposed method can be applied to any kind of rough bed, but it is particularly useful in vegetated beds where long channels are difficult to prepare. In this paper a calibration coefficient is experimentally obtained. In order to perform suitable comparisons with literature data relationships between ε absolute roughness and Manning's n coefficient are deepened. The results are successfully compared with literature experimental data with a very good fit. Finally, a particular dependence of ε values on the vegetation density are explained through further experiences. In conclusion it is possible to state that the proposed method, once calibrated, can provide reliable prediction of absolute roughness in vegetated channels.