Progress in Computational Fluid Dynamics, An International Journal (13 papers in press)

Regular Issues

• Implementation of a New Actuator Disk Model based on BEM Theory in SU2 CFD SOFTWARE  
  by Kaan Yenipazar, Dilek Funda Kurtulus 
  Abstract: The aim of the current study is to develop an alternative actuator disc model in the SU2 (Stanford University Unstructured) software using the blade element theory (BEM) approach. The objective is to reduce computational costs and save time with accurate results. The integrated model has applications in optimizing rotating components such as propellers, wind turbines, axial turbines, etc., as well as accurately predicting wake structures. The new actuator disc model proposed in this study is a steady-state model that assumes an infinite number of blades within the disc domain, making it applicable to varying flow conditions, such as the forward flight of helicopters or aircraft experiencing an angle of attack. The new model was validated by comparing it with experimental data and another high-fidelity tool, which is the rotating frame approach. These comparisons demonstrated that the new model performs accurately and can be a better option than the rotating frame.
  Keywords: SU2; blade element theory; BEM; computational fluid dynamics; CFD; actuator disc; propeller; wind turbine; impeller.
  DOI: 10.1504/PCFD.2024.10064025
   
  
• Numerical Investigation of the Effect of Radiator Placement on Temperature Distribution in a Room  
  by Hande Ufat 
  Abstract: This study analyses the impact of radiator placement on temperature distribution in a room using CFD analysis. Radiators are typically placed under windows or on outer walls. However, in the area under study, where there are large windows extending to the floor on the outer walls, the radiator was positioned on the empty inner wall. Two variations of the analysis were conducted using the ANSYS Fluent program. One variation involved a vertical installation of an aluminium panel radiator of the same length as the existing radiator on the outer wall next to one of the two windows. The other variation involved the installation of two radiators of the same length as the existing radiator next to the windows. The results showed that the room heated up faster when two radiators were used compared to other alternatives. Heating a room with two radiators of equal length and surface temperature results in a faster temperature increase. When a radiator is positioned vertically, the average temperature remains the same as the current situation. Using multiple smaller radiators instead of a single large one that provides the same amount of heat allowed the environment to warm up more quickly.
  Keywords: CFD analysis; thermal comfort; panel radiator; temperature distribution.
  DOI: 10.1504/PCFD.2024.10064248
   
  
• Comparative Analysis on Heat Transfer, between a Steady and Oscillating Jet in a Cavity  
  by Farida Iachachene, Amina Mataoui 
  Abstract: This paper numerically investigates the cooling of a heated rectangular cavity by a cold slot jet. The study aims to examine the effect of the jet location inside the cavity (Lf and Lh) and Reynolds number on heat transfer, using URANS turbulence modelling. Different flow behaviours, including oscillatory and steady flows, are generated depending on the jet location inside the cavity. The study identifies and discusses the optimal jet locations for achieving optimal cavity cooling. The results indicate that the lateral placement of the jet has a negligible effect on heat transfer across all cavity walls. Additionally, oscillatory flow consistently expands the heat exchange zone along all three walls, resulting in a wider effective exchange area compared to steady flow conditions. The study proposes optimised jet positions within the cavity for specific wall cooling requirements. By considering the optimal combination of jet height and impinging distance, the cooling performance can be optimised.
  Keywords: jet-cavity interaction; heat transfer; URANS; finite volume method; oscillatory flow; steady flow; slow jet; CFD; jet location; optimal jet locations.
  DOI: 10.1504/PCFD.2024.10064417
   
  
• Numerical investigation of lucid spherical cross-axis flow turbine concerning changeover on its geometrical parameters in a pipeline compared to a channel  
  by Hamidreza Zarei, Mahmoud Pasandidehfard 
  Abstract: This paper presents an investigation on the performance of a lucid spherical turbine. To verify the numerical predictions the experimental results of Bachant and Wosnik have been used. Drag and power coefficients have been used to compare with the data for the water inlet velocity 1m/s and different non-dimensional tip-speed-ratio. Two airfoil sections, NACA 2412 and NACA 64(3)418, have been selected to design the turbine blades. The impact of four effective blade parameters, inclusive of profile section, chord length, number of blades, and blade twist angels, on turbine performance, is investigated. It can deduce that the power coefficient has increased up to 22% for NACA 2412 compared to the experimental test. Also, the three-bladed turbine possesses the best results among all models. The twist of the blades caused to increase in the power coefficient by 19% and 31% for NACA 2412 and NACA 64(3)418 sections inside the channel respectively.
  Keywords: lucid turbine; asymmetric hydrofoils; lift coefficient; power coefficient; pipeline.
  DOI: 10.1504/PCFD.2024.10064482
   
  
• Computational Analysis of High Speed Super-Cavitating Projectiles for Reduction of Hydrodynamic Drag Using Cavitator Optimisation  
  by Rohini D, Amarkarthik A, Sivaraj G, Haran A.P 
  Abstract: The goal of the paper is the computational analysis of cavitator shape with respect to the forebody of the projectile, which recommends the supercavitation phenomenon. The main target is to provide a phase-changing mechanism for two-phase fluid flow simulation. By employing ANSYS Fluent for disk cavitator, a steady and incompressible two-phase fluid has been analysed, and during the simulation, cavitation is observed. For the designed geometry of the forebody of the projectile, multiphase flow has been chosen, for varying cavitation number of 0.10.01, to optimise the disk cavitators diameter to begin an effective creation of supercavity. The computational analysis of the result displays about the cavity formation, cavity growth, cavity body, and drag prediction for the projectile. To optimise the cavitator diameter, which plays a key role in the formation of supercavitation, 3 mm cavitator disk diameter with a disk to projectile diameter ratio of 0.375 generates the minimum hydrodynamic drag.
  Keywords: super-cavitation projectile; disk cavitator; hydrodynamics; skin friction drag; multiphase flow.
  DOI: 10.1504/PCFD.2024.10064808
   
  
• Analysis of Flow and Thermal Characteristics of a Hybrid Nanofluids within a Microchannel under Magnetic Field  
  by Hakan Türker, Elif Ogut, Erman Aslan 
  Abstract: The study investigates the flow and thermal characteristics of microchannels with varying geometries and boundary conditions. Water is used as the base fluid, with Al2O3 and CuO nanoparticles as additives. The analysis begins with a straight microchannel, followed by comparisons with sinusoidal or sine wave-shaped channels. Additionally, the effects of a magnetic field on a straight microchannel are explored. The numerical simulations, conducted using ANSYS Fluent software, cover Reynolds numbers (Re) of 100, 300, 700, and 1000 in laminar flow, along with volume fractions of 1%, 2%, 3%, 4%, and 5%. A magnetic field intensity of 0.1T is applied for the magnetohydrodynamic (MHD) effect. The results, presented as Nusselt numbers, pressure drop, and thermal performance factor graphs, indicate an increase in Nusselt number with rising Reynolds number and decreasing volume fractions. Pressure drop also rises with increasing Reynolds number and volume fractions.
  Keywords: finite volume method; laminar flow; microchannel; nanofluid; magnetohydrodynamics; convective heat transfer; pressure drop.
  DOI: 10.1504/PCFD.2024.10065361
   
  
• The Optimum Nozzle Exit Position and the Behaviour of a Turbulent Flow in an Ejector Designed for Natural Draft Burner  
  by Chukwunonso. F. Nwoye, Chukwunenye A. Okoronkwo, Godswill Nwaji, Humphrey Okoro, Olisaemeka Nwufor, Emanuel Anyanwu 
  Abstract: This study investigated the near and far stream behaviour of a turbulent flow through an ejector at different axial positions of the nozzle. The study was conducted numerically for a throat-to-nozzle exit axial distance of 5 mm20 mm. The secondary to the primary stream velocity ratio and the magnitude of the boundary layer fluctuation at the nozzle exit increased with the reducing axial distance. The potential core decayed as the flow approached a critical Reynolds number, and the increase in boundary layer fluctuation suppressed the near stream turbulence and momentum transfer by turbulent eddies. The model of the core length as a function of the throat-to-nozzle exit distance revealed a linear profile. Two models described the species concentration along the jet axis as a function of the root mean squared value of the fluctuating velocity because the flow behaved differently near and far streams due to the different controlling mechanisms.
  Keywords: venturi jet; turbulence; nozzle position; velocity ratio; species mixing; initial conditions.
  DOI: 10.1504/PCFD.2024.10065410
   
  
• Multi-Objective Optimisation Approach to Design Passive Micromixers: Taguchi-Based Grey Relational Analysis  
  by Digvijay Ronge, Prashant Pawar 
  Abstract: Micromixers play a crucial role within microfluidic devices to facilitate diffusion mixing. The present study examines the impact of five distinct design parameters of a T-shaped serpentine micromixer namely mixing area shape, micromixer area, channel width, channel spacing, and channel orientation on its mixing efficiency and the pressure drop. Using the Taguchi method of design of experiments (DoE), an orthogonal array (OA) of 27 was constructed, and each experiment was numerically modelled and solved using a computational fluid dynamics (CFD) solver. Signal-to-noise ratio analysis and analysis of variance (ANOVA) were conducted to quantify the impact of each individual parameter. Grey relational analysis (GRA) was employed to optimise the micromixer geometry such that a higher mixing performance is achieved at a lower pressure drop. The optimal micromixer fabricated from Polydimethylsiloxane (PDMS) utilising soft lithography techniques was subjected to experimental validation, showcasing a deviation of 10% from the numerical results
  Keywords: Micromixing; Optimization; Taguchi; ANOVA; Soft Lithography.
  DOI: 10.1504/PCFD.2024.10065412
   
  
• Modelling of multi-species thin film flows based on the transport of ions including conjugate heat transfer applied to corrosion testing  
  by Uwe Janoske, Steffen Seifritz 
  Abstract: Corrosion tests are standardised test procedures where specimen is subjected to different climates in test chambers with defined test cycles. The cycles are a complex scenario of spraying, drying and condensation phases. Aqueous sprays with different salts lead to liquid films and corrosion processes on the specimen. As there are various kinds of salts present which will deposit based on the local concentration of the ions, the stoichiometry and the solubility, the conventional modelling with a given number of species is extremely difficult. Therefore, the modelling approach for handling species was changed to the modelling of the transport of ions in the film including condensation and evaporation. The verification is reported on a simple U-shaped specimen whereas a more complex specimen was used for the validation with experimental results on the basis of a standardised test cycle in corrosion testing.
  Keywords: multi-species; computational fluid dynamics; CFD; fluid films; droplets; dissolution; condensation; evaporation; conjugate heat transfer; corrosion; testing.
  DOI: 10.1504/PCFD.2023.10063153
   
  
• A computational study of air film evolution during droplet impact on a flat solid surface  
  by Umesh, N.K. Singh 
  Abstract: The present study employs the volume of fluid (VOF) method to meticulously resolve the phenomenon of air trapping, capturing its evolution all the way into a spherical air bubble. The impact of velocity and droplet size on the air films progression is investigated; findings reveal that the micro bubble remains detached from the surface for lower impact velocity while it settles down on the surface for higher impact velocities. This outcome holds potential for practical applications requiring air bubble elimination by optimising the impact velocity. Furthermore, the presence of an air film impedes surface-to-droplet heat transfer. The solid surface experiences an increase in wall heat flux where the droplet contacts it, compared to air-solid contact regions due to waters superior thermal conductivity. Notably, maximum wall heat flux occurs at higher impact velocities, amplifying convection heat transfer.
  Keywords: drop impact; two phase simulation; VOF method; air entrapment; impact velocity; droplet size.
  DOI: 10.1504/PCFD.2024.10063785
   
  
• Integrated approach for geometric and kinematic design of centrifugal compressor impellers  
  by Ashwin Shelke, Ashok Mache, Aditya Shelke, Pradyumn Chiwhane, Viral Patel 
  Abstract: Centrifugal compressors are widely used across industries like oil and gas, chemicals, energy generation, and HVAC systems. They convert gas kinetic energy into high-pressure energy. The impeller and diffuser play key roles in this process. Designing the impellers 1D Meridional plane is critical for sizing and operational characteristics. This study establishes an analytical design methodology to determine impeller parameters, satisfying the pressure ratio, efficiency, and mass flow rate requirements. Further, Blade parameters to withstand operational stresses are also determined. Computational fluid dynamics (CFD) validates the model using the SST k-ꞷ model, ensuring reliable results through mesh convergence. The simulation aligns well with analytical parameters. This study provides a strong foundation for optimising analytical compressor design methodologies.
  Keywords: centrifugal compressor; impeller; preliminary design; meridional plane.
  DOI: 10.1504/PCFD.2023.10059900
   
  
• Hydrothermal performance of Al₂O₃/water nanofluid in a vented cavity including hot cylinder covered by a porous layer utilising LTNE approach  
  by Farrokh Mobadersani, Amirreza Jamshid Malekara 
  Abstract: This paper aims to examine the heat transfer rate and flow characteristics of Al₂O₃/water nanofluid in a vented cavity containing a hot square cylinder covered by a layer of porous media. The local thermal non-equilibrium (LTNE) model is employed to couple heat transfer in the solid matrix and nanofluid of the porous domain. The governing equations are numerically solved using the finite element method. Effects of thermal conductivity ratio, Darcy number, Reynolds number, porous layer thickness, dimensionless heat transfer coefficient, and cylinder size, are investigated. The outcomes reveal that at Re = 50, inserting the porous layer can enhance the average Nusselt number by 122% compared to the non-porous case. Furthermore, based on the calculated performance evaluation criterion, the use of a porous layer provides effective hydrothermal performance in low Reynolds numbers. The results indicated that implementing local thermal equilibrium in higher Reynolds and Darcy numbers leads to unreliable results.
  Keywords: vented cavity; mixed convection; nanofluid; local thermal non-equilibrium; LTNE; performance evaluation criteria; PEC.
  DOI: 10.1504/PCFD.2024.10063442
   
  
• Numerical study for separation of particles in helical microchannel  
  by U.D. Nimbalkar, Apoorv Sureshkumar Mishra, Pankaj E. Rawool, V.K. Agrawal 
  Abstract: The present work was aimed at studying the Dean flow pattern in the cross-section of the helical microchannel and its effect on the inertial focusing of bloodstream particles. The Dean flow, a fundamental phenomenon in fluid dynamics, illustrates fluid flow through curved geometries where centrifugal force interacts with pressure gradient. The rectangular, aspect ratio 0.8 and 0.6, and circular 80 μm diameter cross-sections of same axial pitch were analysed for Reynolds number ~ 40, Dean number ~ 9 and Ratio of lift-to-drag forces ~ 0.5. Appreciable focusing was observed as a part of numerical studies, leading to a fine stream of particles at the outlet. The results were analysed and compared with the previous studies. Hence, a rectangular cross-section helical microchannel design is proposed for particle separation that can be fabricated with any suitable polymer.
  Keywords: particle separation; inertial focusing; helical microchannel; microfluidics; Dean flow.
  DOI: 10.1504/PCFD.2024.10064022