In this paper the laminar flow in the rectangular channel bends is simulated using numerical techniques. The turning angle of the channel bend and the area ratio of the channel cross-section are two important parameters to be examined. For flow simulation, the body fitted 3-D continuity and momentum equations are used and a body fitted general purpose code is developed. The existing results of a tied-diriven cavity and the experimental results from a 90 degree square bend were used for code validation. After the code validation, the effect of the area change in the 90 degree bend is examined.The numerical results indicated that increasing the area causes changes in the flow pattern, in turn, which has a direct impact on pressure drop. Similar results were obtained for other bend angles including 30,60,120,150 and 180 degree bends. The results showed that increased bend turning angle increases the pressure drop which is in good agreement with existing experimental data.

Measuring flow rate precisely in laminar flow has been a difficult task, especially when utilizing a Coriolis mass flow meter (CMFM) for low flow rate measurements. The meter often under reads the mass flow rate, making it less useful in these conditions. The dominant factor affecting the CMFM's performance in laminar regions is secondary flow, which overshadows the generated Coriolis force, leading to an under-reading of flow rate. Previous studies have indicated that tube curvature is the most significant parameter affecting secondary flow generation and the overall performance of the meter. An omega-shaped tube configuration featuring a continuous curvature has been identified as the optimal shape for maximizing a CMFM device’s performance in laminar flow. The purpose of the investigation is to study and compare the efficiency of various Omega tube designs that have undergone slight geometric alterations. Four different configurations were evaluated for maximum time lag by vibrating at their respective natural frequencies and keeping the sensor position along the centerline of the tube configuration.

The superhydrophobic surfaces have many applications, including skin friction reduction, antiicing, anti-fouling, and self-cleaning surfaces. Also, with the precise design of these surfaces, it is possible to increase the heat transfer coefficient in the condensation heat transfer. In recent years, a variety of methods have been proposed for the fabrication of the superhydrophobic surfaces, some of which are very complex and not applicable for industrial uses. In this paper, a nanocomposite superhydrophobic coating is produced in a simple and applicable way for large surfaces. Using this method, a superhydrophobic surface with surface structures in multi-scale and with a sliding angle of less than 5 degrees is obtained. After evaluating the specification of superhydrophobic surfaces, slip length measurement of the coating is performed using a fabricated measurement system. It should be noted that the slip length of the superhydrophobic surface is a characteristic feature of these surfaces and always its measurement is associated with challenges. In this research, the slip length of the created coating was measured by use of the proposed measurement system. The results show that the slip lengths of about 40-500 microns can be achieved by use of the proposed measurement system.

In this paper the results of numerical simulations for heat transfer of a nanofluid flow inside a counter flow heat exchanger is presented. Effects of addition of the Al2O3 nanoparticles on the entropy generation of the system are investigated. Single fluid model is used for simulation of the nanofluid flow. Analytical and experimental formulations are used for density, specific heat, viscosity and conductivity of nanofluid. Finite volume method (FVM) has been used for numrerical simulation and SIMPLE algorithm is applied for pressure velocity coupling. It is found that adding nano particles in annulus, causes a little incerement in entropy generation which can be overlooked. On the other hand, the increasing of volume fraction of nanoparticles leads to ascend heat transfer coefficient (U ) and total heat transfer (Q) significantly, and it results in decreased entropy number (Ns).

The use of the classical Boussinesq approximation is a straightforward strategy for taking into account the buoyancy effect in incompressible solvers. This strategy is highly effective if density variation is low. Whenever the density variation is high, this can cause considerable deviation from the correct prediction of fluid flow behavior and the accurate estimation of heat transfer rate. In this study, an incompressible algorithm is suitably extended to solve high-density-variation fields caused by strong natural-convection with mixing of oxygen and nitrogen in unsteady laminar compressible flow in a cavity. The continuity, momentum, energy and species equations are discretized based on finite volume methods and then numerically solved with extended algorithm with SIMPEL method. This new algorithm is capable of solving both Boussinesq and non-Boussinesq regimes.The fluid is assumed to be calorically an ideal gas and its thermodynamic properties depend on temperature and pressure. The extended algorithm is then verified by solving the benchmark convecting cavity problem at Rayleigh 106 and a temperature range of e=0.01-0.6. The results show that the method can vigorously solve unsteady mixing flow fields with extreme density variation

In this paper, the laminar incompressible flow equations are solved by an upwind least-squares meshless method. Due to the difficulties in generating quality meshes, particularly in complex geometries, a meshless method is increasingly used as a new numerical tool. The meshless methods only use clouds of nodes to influence the domain of every node. Thus, they do not require the nodes to be connected to form a mesh and decrease the difficulty of meshing, particularly around complex geometries. In the literature, it has been shown that the generation of points in a domain by the advancing front technique is an order of magnitude faster than the unstructured mesh for a 3D configuration. The Navier–Stokes solver is based on the artificial compressibility approach and the numerical methodology is based on the higher-order characteristic-based (CB) discretization. The main objective of this research is to use the CB scheme in order to prevent instabilities. Using this inherent upwind technique for estimating convection variables at the mid-point, no artificial viscosity is required at high Reynolds number. The Taylor least-squares method was used for the calculation of spatial derivatives with normalized Gaussian weight functions. An explicit four stage Runge-Kutta scheme with modified coefficients was used for the discretized equations. To accelerate convergence, local time stepping was used in any explicit iteration for steady state test cases and the residual smoothing techniques were used to converge acceleration. The capabilities of the developed 2D incompressible Navier-Stokes code with the proposed meshless method were demonstrated by flow computations in a lid-driven cavity at four Reynolds numbers. The obtained results using the new proposed scheme indicated a good agreement with the standard benchmark solutions in the literature. It was found that using the third order accuracy for the proposed method could be more efficient than its second order accuracy discretization in terms of computational time.