Scrutiny of Unsteady Flow and Heat Transfer in a Backward-Facing Step Under Pulsating Nanofluid Blowing Using the Eulerian-Eulerian Approach

2017 ◽  
Vol 35 (1) ◽  
pp. 93-105 ◽  
Author(s):  
I. Zahmatkesh ◽  
E. Torshizi
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Unsteady Flow ◽  
Water Flow ◽  
Base Fluid ◽  
Phase Model ◽  
Backward Facing Step ◽  
Two Phase ◽  
Flow And Heat Transfer ◽  
Non Equilibrium

AbstractIn this paper, unsteady flow and heat transfer of water flow in a backward-facing step under pulsating nanofluid blowing are studied numerically. Attention is focused to examine the impact of this type of blowing and its pertinent parameters on the heat transfer performance and to detect possible non-equilibrium between the base fluid and the nanoparticles inside the flow field. To this aim, the Eulerian-Eulerian two-phase model is adopted. This approach consists of separate equation sets for the base fluid and the nanoparticles. So, it provides details of the flow field for each of the constituents, separately. Computations are undertaken for different cases and the consequences of the frequency, amplitude, and the mean velocity of the pulsating blowing as well as the type, diameter, and the volume fraction of the nanoparticles therein on the heat transfer characteristics are analyzed. It is found that in addition to thermal conductivity of the blown nanoparticles, their penetration into the water flow is an important trait that has a momentous role on the heat transfer rate. In the current Eulerian-Eulerian simulation, temperature distributions of the base fluid and the nanoparticles are similar but the corresponding velocity fields are quite distinct. This reveals a kind of non-equilibrium between the base fluid and the nanoparticles inside the flow that invalidates equilibrium approaches (e.g., the single-phase model or the two-phase mixture model) for the description of the problem.

Analysis of Runback Water Flow on Anti-Icing Surface Using Volume-of-Fluid Method

2017 ◽  
Author(s):  
Mei Zheng ◽  
Wei Dong ◽  
Zhiqiang Guo ◽  
Guilin Lei
Keyword(s):  
Heat Transfer ◽  
Water Flow ◽  
Thin Liquid Film ◽  
Flow Characteristics ◽  
Volume Of Fluid ◽  
Complex Model ◽  
Two Phase ◽  
Flow And Heat Transfer ◽  
Liquid Film Flow ◽  
The Mathematical Model

The runback water flow and heat transfer on the surface of aircraft components has an important influence on the design of anti-icing system. The aim of this paper is to investigate the water flow characteristics on anti-icing surface using numerical method. The runback water flow on the anti-icing surface, which is caused by the impinging supercooled droplets from the clouds, is driven by the aerodynamic shear forces and the pressure gradient around the components. This is a complex model of flow and heat transfer that considers flow field, super-cooled droplets impingement and runback water flow simultaneously. In this case of gas-liquid two phase flow, the Volume-of-Fluid (VOF) method is very suitable for the solution of thin liquid film flow so that it is applied to simulate the runback water flow on anti-icing surfaces in this paper. Meanwhile, the heat and mass transfer of the runback water flow are considered in the calculation using the User-Defined Functions (UDFs) in ANASYS FLUENT. The verification is conducted by the comparison with the results of the experimental measurement and the mathematical model calculation. The effect of the airflow velocity and contact angle on the water flow are also considered in the numerical simulation.

Rotating Al2O3-H2O nanofluid flow and heat transfer with internal heating, velocity slip and different shapes of nanoparticles

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Saeed Dinarvand ◽  
Mohammadreza Nademi Rostami
Keyword(s):  
Heat Transfer ◽  
Prandtl Number ◽  
Phase Analysis ◽  
Base Fluid ◽  
Velocity Slip ◽  
Analysis Method ◽  
Internal Heating ◽  
Two Phase ◽  
Content Type ◽  
Flow And Heat Transfer

PurposeThis research numerically investigates the steady laminar 3D forced convective flow and heat transfer of a rotating Al2O3/water nanofluid past a linearly stretching sheet with the help of a novel two-phase analysis method by considering different nanoparticle shapes as well as velocity slip boundary condition plus internal heating.Design/methodology/approachThe authors’ novel two-phase analysis method implements the Jang and Choi model for the effective thermal conductivity and incorporates it with Tiwari–Das mathematical model. Besides, the shape factors of the nanoparticles have also taken into account using the Timofeeva model for effective dynamic viscosity. The Prandtl number of the base fluid is kept constant at 6.2 and the temperature of the nanoparticles as well as the base fluid molecules is assumed to be 300 K. In short, after using the similarity transformation method, the obtained dimensionless nonlinear ODEs are numerically solved using the bvp4c built-in function from MATLAB. The governing parameters are solid volume concentration, rotation parameter, velocity slip parameter, heat generation or absorption parameter and Prandtl number of the base fluid.FindingsIt is argued that when the cylindrical shape for alumina is chosen, the maximum values for skin friction coefficients and local Nusselt number have been obtained among the other shapes. Further, the velocity slip enhancement in this problem will lead to a drastic reduction in the foregoing quantities of engineering interest.Originality/valueTo the best of the authors’ knowledge, this research is a novel attitude to two-phase nanofluid model.

Two-Phase Study of Fluid Flow and Heat Transfer in Gas-Solid Flows (Nanofluids)

2011 ◽  
Vol 110-116 ◽  
pp. 3878-3882 ◽  
Author(s):  
Hossein Afshar ◽  
Mehrzad Shams ◽  
Seyed Mojtba Mousavi Nainian ◽  
Goodarz Ahmadi
Keyword(s):  
Heat Transfer ◽  
Transfer Rate ◽  
Base Fluid ◽  
Volume Fraction ◽  
Maxwell Model ◽  
Two Phase ◽  
Flow And Heat Transfer ◽  
Gravity Forces ◽  
Phase Study ◽  
Two Phase Heat Transfer

In this paper, two phase heat transfer of a mixture of nanopaticles in air flow as a type of nanofluid is studied. Volume fraction of the dispersed phase is very low (less than 1%). Nanoparticles travel in the base fluid due to drag, brownian and gravity forces and are tracked according to lagrangian approach. Effect of reduced specific heat of nanofluid on heat transfer is considered. The results show an increase in heat transfer rate which is very much more than that predicted by the Maxwell model.

Effect of thermal radiation on magnetohydrodynamics nanofluid flow and heat transfer by means of two phase model

2015 ◽  
Vol 374 ◽  
pp. 36-43 ◽  
Author(s):  
Mohsen Sheikholeslami ◽  
Davood Domiri Ganji ◽  
M. Younus Javed ◽  
R. Ellahi
Keyword(s):  
Heat Transfer ◽  
Thermal Radiation ◽  
Phase Model ◽  
Nanofluid Flow ◽  
Two Phase ◽  
Flow And Heat Transfer

Nanotechnology as Effective Passive Technique for Heat Transfer Augmentation

2018 ◽  
pp. 1-49
Keyword(s):  
Heat Transfer ◽  
Base Fluid ◽  
Single Phase ◽  
Particle Dispersion ◽  
Two Phase ◽  
Flow And Heat Transfer ◽  
Fluid Properties ◽  
And Behaviors ◽  
Passive Technique ◽  
Definition Of

Nanofluids are fluids containing the solid nanometer-sized particle dispersion. Two main methods are introduced in this chapter, namely single-phase and two-phase modeling. In first method, the combination of nanoparticle and base fluid is considered as a single-phase mixture with steady properties, and in the second method, the nanoparticle properties and behaviors are considered separately from the base fluid properties and behaviors. Moreover, nanofluid flow and heat transfer can be studied in the presence of thermal radiation, electric field, magnetic field, and porous media. In this chapter, a definition of nanofluid and its applications have been presented.

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