A free convective unsteady visco-elastic flow through porous medium of variable permeability bounded by an infinite vertical porous plate with variable suction, constant heat flux under the influence of transverse uniform magnetic field has been investigated in the present study. The permeability of porous medium fluctuates with time about the constant mean. Approximate solutions for mean velocity, transient velocity, mean temperature and transient temperature of non-Newtonian flow and skin friction are obtained. The effects of various parameters such as Pr (Prandtl number), Gr (Grashof number), M (Hartmann number),  w (frequency parameter) and k0 (mean permeability parameter) on the above are depicted, skin friction, amplitude and phase are shown graphically and discussed. Expressions for fluctuating parts of velocity ‘Mr’ and ‘Mi’ are found and plotted graphically, effects of different parameters on them are discussed.

In this paper, the application of the surface mass transfer optimization in shock wave-boundary layer interaction control at off-design conditions of transonic aircraft wing is presented. The suction or injection parameters include for example its position on the airfoil, its angle, the length of the hole and the rate of the injected or sucked flow. The optimization process is carried out using an efficient Genetic Algorithm (GA) method. The compressible viscous flow equations in Reynolds Averaged form are solved together with a twoequation k-epsilon turbulence model to accurately compute the objective function. Four different objective functions are introduced including maximum lift to drag ratio, minimum drag coefficient, maximum lift to drag ratio with no drag increment and minimum drag coefficient with no lift decrement. Effectiveness of each objective function is examined by comparing the optimum results in terms of the flow control parameters and flow characteristics.

One of the important ways of improving axial compressor performance is to control the tip leakage flow near the endwall region. Numerical computations were conducted to investigate the impact of blade tip suction on the axial compressor cascade performance in current paper. Three suction schemes located on the blade tip with different chordwise coverage were investigated in total. The results show that the cascade overall performance can be effectively enhanced by the proper suction scheme on the blade tip and the best scheme should be arranged at slightly downstream of the onset point of the tip leakage vortex (TLV). The control effectiveness and mechanisms are different for the different suction schemes. For the suction scheme covering the starting point of TLV, the onset point of TLV is shifted downstream, while an additional induced leakage flow near the blade leading edge is generated resulting in the increase of mixing loss. It is more effective when the structure of the main TLV is destroyed and divided into different parts by applying the blade tip suction arranged slightly behind the onset point of TLV. In addition, the blade loading is redistributed near the blade tip after the blade tip suction and the total pressure loss caused by the suction slots should also be considered in the design process.

Flow-induced instabilities are one of the major challenges in the design of aerospace structures. Numerous passive and active control methods have been used to reduce the flow-induced oscillations of square cross-section cylinder as the basic geometry for structures with sharp corners. The suction and blowing flow control method are one of the most effective approaches for controlling the flow and consequently reducing the vibrations resulting from the aerodynamic forces, which so far are not considered for an elastically-mounted square cylinder which fluctuates freely in the transverse direction. Therefore, in this paper, suction and blowing flow control methods have been used separately to suppress flow-induced oscillations. In the suction-based method, a slut is placed on the front surface of the cylinder and in the blowing-based method another slot is inserted on the back surface of the cylinder. In the present study, the effect of suction and blowing velocities as well as the effect of suction and blowing slut lengths on the efficiency of the flow control approach was evaluated. According to the flow-structure interaction simulations, it is observed that the applied flow control method has been able to reduce flow-induced vibrations appropriately.

Dear editor, Suction syringes are utilized to produce blisters for epidermal grafts, as well as for treating localized and stable vitiligo with better cosmetic acceptability. However, the suction process should be fast to save time. The 3-way cannulasyringe can produce blisters within 1 to 2 h (1). Moreover, the failure of this device at-300 to-400mmHg to produce a suction blister and the incidence of incomplete blisters at the site are seen in about 20 to 30% of cases (2, 3). The success rate is improved by the application of heat, intralesional injection of normal saline and local anesthetic agents over the donor site. Thus, the 3-way cannula-syringe is a little cumbersome and time-consuming device...

Temporal flow characteristics of a 3D centrifugal impeller suction system were numerically studied in vacuum conditions. The blockage of the high-speed rotating impeller appeared, which greatly dropped the suction of the layer suction device. The temporal flow characteristics of the 3D centrifugal impeller suction system were worthy of attention in vacuum conditions. Separation vortices were generated near the blade suction surface. The blocking mechanism of the passage was further analyzed at different extremely low flow rates through the time-space evolution of the streamline. The Q-criteria was introduced to analyze the vortex evolution within the fluid domain of the impeller. Vortex evolution law was captured—the vortices always generated near the suction surface of the blade and moved to the pressure surface of the adjacent blade in the same passage and disappeared. The uniform distribution of three stall cells was captured through the diagram of turbulent kinetic energy. The flow rate increased, and the vortex evolution period gradually decreased. The comparison of pressure fluctuations in different conditions further demonstrated the flow mechanism at the vacuum flow rate was different from that at low flow rates. The sharp increase of pressure fluctuations near the blade pressure surface was consistent with the phenomenon near the suction surface. The pressure fluctuation at extremely low flow was mainly composed of scattered fluctuations caused by fluid separation. The steady and unsteady characteristics described the internal flow characteristics of this suction system at vacuum-flow rates. Theresults provide a profound design for vacuum cleaners.

The problem of unsteady Stokes flow of certain Newtonian fluids in a circular pipe of uniform cross section is discussed. The pipe is uniformly porous. The unsteady Navier-Stokes equations for the system in cylindrical polar coordinates have been solved analytically to obtain a complete description of the flow. The solution of the flow equations subject to the slip boundary conditions leads to the detailed expressions for axial and radial components of velocity and the pressure distribution depending on position coordinates and time. As a special case we have presented the situation when no-slip boundary conditions are implemented. The velocity profile is analyzed for different values of the flow parameters like Womersley number, slip length and time.

In this study, the simultaneous effect of suction and blowing on the boundary layer and the effect of control parameters on the flow separation from a NACA 0012 airfoil is numerically analyzed. Reynolds number is considered 500000 , and the shear stress transport (SST) k-w turbulence model is used to estimate eddy viscosity. The airfoil is supposed to be 2-D. To validate the numerical results, they were compared with reported experiments. In the flow control by simultaneous suction and blowing, the location of the suction jet was 0.1 of the airfoil chord from the fixed leading edge, and that of the blowing jet was 0.5, 0.7, and 0.9 of the airfoil chord from the leading edge. When the blowing location is at 0.5 of the airfoil chord, better results are observed than I n; other locations. An increase in suction jet velocity increases the lift-drag ratio between 22% and 55%. Also, increasing the blowing jet velocity increases this ratio between 43% and 55%. Horizontal blowing has the most negligible effect on improving aerodynamic characteristics. Based on the results, at the angle of attack of 16°, blowing is most effective in the flow control at  with an approximate velocity of half the free stream velocity. In this condition, vertical suction has the best effect , and the lift-drag  ratio will increase by 76%.

An analysis is carried out on the natural or free convective magnetohydrodynamic flow of a non-Newtonian Jeffrey fluid with a Hall current, heat source, and variable suction near vertical plate.Using a flexible, widely validated variable finite element method, the governing nonlinear partial differential equations be transformed into linear partial differential equations using similarity variables, and this equations along with the associated boundary conditions be then solved numerically.The fluctuation of important parameters in the thermal and hydrodynamic boundary layers be thoroughly examined, and the findings are displayed visually. Additionally, a comparison study is offered to reduce verification and arrive at a excellent consensus. This model is beneficial for geothermal reservoirs, subterranean power transmission, MHD pumps, accelerators, and flow metres, as well as industrial heat management, geological flows within mud cover, etc.