Slip-flow and heat transfer of chemically reacting micropolar fluid through expanding or contracting walls with Hall and ion slip currents

AbstractThe present article deals with the effects of velocity slip, chemical reaction on heat and mass transfer of micropolar fluid in expanding or contracting walls with Hall and ion slip currents. Assume that there is symmetric suction or injection along the channel walls, which are maintained at nonuniform constant temperatures and concentrations. The governing Navier–Stokes equations are reduced to nonlinear ordinary differential equations by using similarity transformations then solved numerically by quasilinearization technique. The effects of various parameters such as wall expansion ratio, chemical reaction parameter, Prandtl number, Schmidt number, slip parameter, Hall and ion slip parameters on nondimensional velocity components, microrotation, temperature and concentration are discussed in detail through graphs. It is observed that the concentration of the fluid is enhanced with viscosity. Further, the temperature and concentration of the fluid are increased whereas the microrotation is decreased for an expansion or contraction of the walls

GPS Receiver Simplification for Low cost Applications and Multipath Mitigation Analysis on SDR based Re configurable Software Receiver

Many modern position-based applications rely heavily on the Global Navigation Satellite System (GNSS). Most applications require precise position data obtained through sophisticated hardware with a high computational capacity in the receiver. Some cost-effective applications may not require precise position data and require less complex signal processing. The use of efficient hardware and signal processing techniques to reduce the overall cost of a GNSS receiver is an active research topic. This paper considers Global Positioning System (GPS) constellation and proposes two factors to reduce the receiver complexity: sampling frequency and the number of tracking channels. A Keysight GNSS signal generator to record GPS signals, a Software Defined Radio board and a software-based GPS receiver are used in the experimentation. The sampling frequencies are 40, 20, 10 and 5 MHz considered, and tracking channels are reduced from 12 to 6 and then 4. The increase of error in the receiver position with 6 and 4 satellites is considerably small, but the number of tracking channels and signal processing requirements are reduced considerably. The GPS signals are affected by many errors; one of the significant sources of error is multipath propagation. Three distinct GPS multipath scenarios are generated for four satellite signal combinations with the GNSS simulator for the receiver performance analysis. Three multipath mitigation techniques, namely Early Minus Late (EML), Narrow correlator (NC) and strobe correlator (SC) methods, are considered because of their simple structure and fewer signal processing requirements. The error reductions of three multipath scenarios are compared, and the SC method performs better in all three multipath scenarios

Multi GNSS IRNSS L5 IRNSS S1 and GPS L1 Hybrid Simulator A Reconfigurable Low cost Solution for Research and Defence Applications

Satellite-based positioning field of research is growing rapidly as there is an increase in demand for precise position requirements in various civil and commercial applications. There are many errors that affect the GNSS signals while propagation from satellite to receiver, which eventually induces errors in pseudo-range measurements. In order to assess the receiver characteristics for a specific error condition, the real-time signals may not be appropriate, and it is challenging to perform repeated experiments with the same error condition. The advantage of the GNSS simulator is that users can model the different scenarios for any given location on the globe, which are repeatable at any point of time. The conventional hardware simulators are expensive and have few limitations. In this paper, a reconfigurable hybrid simulator is proposed with some advantages over traditional hardware simulators, such as low cost, reconfigurability, and controllability over fundamental parameters. It can be able to record intermediate stage data, which makes it more suitable for the GNSS research field. The proposed multi-GNSS simulator considered implementing IRNSS-L5, IRNSS-S1, and GPS-L1 band signals. A general-purpose computer can perform the necessary calculations for signal generation. The hybrid simulator can be able to generate the digital I/Q data, which can be stored as I/Q data or can be connected to a general-purpose SDR (Software Defined Radio) for RF signal generation (bladeRF in this case). The I/Q data can be used with the software receiver to analyse the receiver performance concerning the specific error. The generated GNSS signals are validated with software and hardware receivers, and the obtained position is observed as expected.&nbsp

Chemically reacting micropolar fluid flow and heat transfer between expanding or contracting walls with ion slip, Soret and Dufour effects

The aim of the present study is to investigate the Hall and ion slip currents on an incompressible free convective flow, heat and mass transfer of a micropolar fluid in a porous medium between expanding or contracting walls with chemical reaction, Soret and Dufour effects. Assume that the walls are moving with a time dependent rate of the distance and the fluid is injecting or sucking with an absolute velocity. The walls are maintained at constant but different temperatures and concentrations. The governing partial differential equations are reduced into nonlinear ordinary differential equations by similarity transformations and then the resultant equations are solved numerically by quasilinearization technique. The results are analyzed for velocity components, microrotation, temperature and concentration with respect to different fluid and geometric parameters and presented in the form of graphs. It is noticed that with the increase in chemical reaction, Hall and ion slip parameters the temperature of the fluid is enhanced whereas the concentration is decreased. Also for the Newtonian fluid, the numerical values of axial velocity are compared with the existing literature and are found to be in good agreement

Chemically reacting micropolar fluid flow and heat transfer between expanding or contracting walls with ion slip, Soret and Dufour effects

The aim of the present study is to investigate the Hall and ion slip currents on an incompressible free convective flow, heat and mass transfer of a micropolar fluid in a porous medium between expanding or contracting walls with chemical reaction, Soret and Dufour effects. Assume that the walls are moving with a time dependent rate of the distance and the fluid is injecting or sucking with an absolute velocity. The walls are maintained at constant but different temperatures and concentrations. The governing partial differential equations are reduced into nonlinear ordinary differential equations by similarity transformations and then the resultant equations are solved numerically by quasilinearization technique. The results are analyzed for velocity components, microrotation, temperature and concentration with respect to different fluid and geometric parameters and presented in the form of graphs. It is noticed that with the increase in chemical reaction, Hall and ion slip parameters the temperature of the fluid is enhanced whereas the concentration is decreased. Also for the Newtonian fluid, the numerical values of axial velocity are compared with the existing literature and are found to be in good agreement

Slip-flow and heat transfer of chemically reacting micropolar fluid through expanding or contracting walls with Hall and ion slip currents

The present article deals with the effects of velocity slip, chemical reaction on heat and mass transfer of micropolar fluid in expanding or contracting walls with Hall and ion slip currents. Assume that there is symmetric suction or injection along the channel walls, which are maintained at nonuniform constant temperatures and concentrations. The governing Navier–Stokes equations are reduced to nonlinear ordinary differential equations by using similarity transformations then solved numerically by quasilinearization technique. The effects of various parameters such as wall expansion ratio, chemical reaction parameter, Prandtl number, Schmidt number, slip parameter, Hall and ion slip parameters on nondimensional velocity components, microrotation, temperature and concentration are discussed in detail through graphs. It is observed that the concentration of the fluid is enhanced with viscosity. Further, the temperature and concentration of the fluid are increased whereas the microrotation is decreased for an expansion or contraction of the walls

MHD slip flow of chemically reacting UCM fluid through a dilating channel with heat source/sink

The present article explores the effects of uniform heat source and first order destructive chemical reaction on an upper convected Maxwell fluid through an expanding or contracting channel with the porous slip condition at the upper plate. It is assumed that the fluid is sucked or injected through the upper plate. The temperature and concentration at the plates is maintained constant. Using suitable similarity transformations, nonlinear coupled ODEs are developed from the governing PDEs. The subsequent ODEs are converted into a first order system and integrated via shooting method. The effect of various prominent parameters on heat, flow and mass transfer characteristics are studied in detail through graphs and tables. The present results suggest that the presence of chemical reaction and heat source yields in the reduction of concentration and of the enhancement of temperature the fluid. It is also observed that the wall expansion shows an increasing effect on the radial velocity component, but the slip parameter exhibits an opposing effect. The viscous case has been studied as a special case where the present results are found to be close to the earlier ones. The flow of such nonlinear viscoelastic fluids has important applications in separation processes like petroleum and medical industries

Numerical Analysis Of Natural Convective Flow And Heat Transfer Of Nanofluids In A Vertical Rectangular Duct Using Darcy-Forchheimer-Brinkman Model

In this paper, natural convective flow and heat transfer of nanofluids in a vertical rectangular duct filled with porous matrix is investigated. The Darcy-Forchheimer-Brinkman model is used to represent the fluid transport within the porous medium covering the parametric ranges of 1 ≤ Gr ≤ 25,0 ≤ Br ≤ 8, and 0.0001 ≤ Da≤ 100. Also, pure water and five different types of nanofluids (Cu, diamond, TiO2, Ag and SiO2) are used with a volume fraction range of 0% ≤ Ø ≤0.2%. The governing nonlinear, coupled partial differential equations for the two-dimensional laminar, steady flow and heat transfer are solved numerically by a finite difference method with second order accuracy. It is found that the heat transfer is enhanced due to the use of a nanofluid. Further, it is noticed that an increase in the Darcy or Grashof or Brinkman numbers, or the aspect ratio parameter increase the flow and heat transfer characteristics; whereas the inertial or the viscosity ratio parameters reduce the flow and heat transfer characteristics. It is observed from 2-D graphs that the fluid rise up from the middle portion of the vertical wall and flow down along the two horizontal walls forming symmetric rolls with clockwise and counter-clockwise rotation inside the cavity. The temperature contours in 2-D are smooth curves which span the entire enclosure, and they are generally symmetry with respect to the horizontal symmetric line. The results obtained reveal many interesting behaviors that warrant further study on the heat transfer enhancement due to the nanofluids