Progress in Computational Fluid Dynamics, An International Journal (19 papers in press)

Regular Issues

• Swimming Performance of Two-Dimensional Undulating Fins with Different Wavelengths in Near-Wall Environment  
  by Xiangxiang Wang, Hualong Xie, Jialin Li 
  Abstract: To investigate the ability of undulating fins with different wavelengths to utilise the wall effect to enhance swimming efficiency, this paper simulates the forward motion of undulating fin models with different wavelengths at different distances from the wall, using a two-dimensional cutaway model of the pectoral fin of the skate as an object of study. The authors find that the swimming speed and propulsive force of the long-wavelength model are significantly better than those of the shorter-wavelength model. Moreover, the kinematic states of the undulating fin models with different wavelengths are more obviously changed when they swim near the wall, and the longer the wavelength is, the greater the gain in swimming performance obtained by swimming near the wall. This paper explains why the longer the wavelength, the more affected by the wall effect through the change of the wake vortex, and explains the phenomenon that the lateral input power becomes larger near the wall through the change of the pressure.
  Keywords: wall effect;undulating fin;vortex structure ;Promoting efficiency.
  DOI: 10.1504/PCFD.2025.10075887
   
  
• Parametric Vernacular: Decoding Climate-Adaptive Modular Design in Concave-Shaped Huizhou Skywell Dwellings through CFD Simulation  
  by Hui Dai, Mengjun Zhu, Hui Shao, Minghan Yang, Decai Gong 
  Abstract: Huizhou traditional dwellings, exemplifying climate-responsive vernacular architecture, have evolved over centuries into a modular system adapted to local climates. This study examines the concave-shaped plan in Chengkan Village, identifying the stepped column height as the core modular unit for skywell geometry. Using a Ming Dynasty dwelling as a prototype, nine parametric skywell variants were created, and their aerodynamic performance was assessed using computational fluid dynamics (CFD), focusing on the aperture-to-base area ratio. Key findings include: first, skywell height has limited impact on wind dynamics (with an influence coefficient of approximately 0.12), confirming the ecological rationality of vertical expansion; second, depth and aperture ratio optimise spatial efficiency and microclimate; and third, inverted trapezoidal forms enhance passive airflow through Venturi effects. This parametric analysis reveals a framework of parametric dominance, evolutionary optimisation, and modular harmony, illustrating how vernacular modularity enables climate adaptation while balancing heritage conservation and environmental performance.
  Keywords: traditional vernacular dwellings; parametric modular system; wind-driven ventilation; computational fluid dynamics simulation; heritage conservation.
  DOI: 10.1504/PCFD.2025.10076575
   
  
• Effects of the Overlap Ratio on the Power and Aerodynamic Coefficients of Semi-Circular and newly developed Parabolic Blade Profiles in a Savonius-Style Wind Turbine  
  by Eusebious Theodynosious Chullai, Subhendu Maity, Bikash Sarkar 
  Abstract: The Savonius wind turbine, a vertical-axis wind turbine, is valued for its simplicity and off-grid power potential. To improve its efficiency, various blade configurations have been explored, with scope for further innovation. This study investigates the effect of the overlap ratio (OR) on a newly developed parabolic blade profile and compares it with a traditional semi-circular profile. Using 2-D simulations with the SST k-? model at Reynolds number = 1.12x 105, results show that at OR = 0.0, the parabolic rotor outperforms the semicircular rotor at all tested tip speed ratios (TSRs), achieving an 11% higher in maximum power coefficient. Further analysis at TSR = 0.8 reveals optimal ORs of 0.15 and 0.10 for the semicircular and parabolic rotors, respectively, improving power coefficients by 6% and 2%. Enhanced aerodynamic interactions at these ORs improve energy capture, supported by lift, drag, and velocity contour analysis.
  Keywords: Savonius wind rotor; parabolic profile; overlap ratio; power coefficient; aerodynamic coefficient; SST k-? turbulence model.
  DOI: 10.1504/PCFD.2025.10076692
   
  
• Numerical Simulation of Active Flexible Filament Dynamics in Fluid Flow using Immersed Boundary Method  
  by Dinesh Kumar Ravada, Ranjith Maniyeri 
  Abstract: This work presents numerical simulation of flexible filament tethered at the bottom of a two-dimensional channel and actuated at its free end using periodic external force. Considering the filament as one-dimensional, a second-order immersed boundary method is used to model the moving fluid-filament interaction. The fluid equations are solved using finite volume based semi-implicit fractional step algorithm. The filament is actuated at its tip resulting in asymmetric forward and backward oscillations. A systematic parametric study is carried out for actuating frequencies of 2, 5 and 10 and Reynolds numbers of 10, 20 and 50.The effect on filament deformation in forward and backward stroke is analysed .Higher actuating frequencies and Reynolds numbers produce greater filament slope angle, strong recirculation zone and complex flow pattern near the filament tip, enhancing mixing but reducing transport capabilities. In contrast, lower frequencies and Reynolds numbers result in weaker mixing but more effective fluid transport.
  Keywords: Flexible filament; Immersed boundary method; Fluid-structure interaction; Frequency; Reynolds number; mixing enhancement.
  DOI: 10.1504/PCFD.2026.10077779
   
  
• CFD investigation of head loss in limestone-water slurry flow through circular and elliptical pipe bends  
  by Jivanjyoti Mishra, Manas Ranjan Behera, Priyaranjan Panda, Anjan Kumar Mishra, Trilochan Pradhan, Rasmi Ranjan Jena, Asisha Ranjan Pradhan 
  Abstract: The hydraulic performance of slurry pipelines is strongly influenced by bend geometry, as unsuitable designs can lead to excessive head loss and energy consumption. This study employs a multiphase computational fluid dynamics approach to evaluate the effect of bend configuration on head loss for slurry flow. Simulations were performed using Eulerian-Eulerian multiphase model with the SST k turbulence model to capture fluid-particle interactions accurately. Circular and elliptical bends with area ratios of 1.5 to 2.5 were examined across flow velocities of 1.5-3.0 m.s1. Model predictions showed good agreement with in-house experimental data for limestone-water slurry, with a maximum deviation of +-8%. Results reveal that head loss increases with velocity, solids concentration, and area ratio. Elliptical bends exhibited 6%-7% higher losses than circular bends under identical conditions. The findings offer practical insights for optimising bend geometry to reduce energy demand in slurry transport systems.
  Keywords: computational fluid dynamics; CFD; slurry transport; pipe bend geometry; area ratio; head loss.
  DOI: 10.1504/PCFD.2026.10078192
   
  
• Evolution of Different Rheological Parameters for Biofilm Suppression During Implant: a CFD study  
  by Bratajit Basu, Dimpal Khambhati, Vishakha Khambhati, Khemraj Deshmukh 
  Abstract: Biofilm formation presents a significant obstacle in infections related to implants, as traditional antimicrobial approaches frequently encounter constraints. CFD simulations were executed in COMSOL Multiphysics 5.6, incorporating laminar flow and FSI modules, under no-slip conditions, for both Newtonian and non-Newtonian blood flow. TPMS-based I-graph wrapped package (IWP) scaffolds with 50% and 70% porosity and a solid scaffold of 10% porosity were analysed across six inlet velocity profiles (sinusoidal and physiological) from V1 to V6. Rheological parameters (shear rate, shear stress, strain, and axial velocity) were measured on 15 different points (P1 to P15) at the T cycle. Newtonian flow exhibited smooth responses with peak shear stress (38,304.88 Pa, V6), whereas non-Newtonian flow exhibited higher fluctuations and peaks, mainly under sinusoidal flow (V3), with maximum strain (3.371
  Keywords: Biofilm suppression; CFD analysis; TPMS; rheological parameters; non-Newtonian; FSI.
  DOI: 10.1504/PCFD.2026.10078315
   
  
• Fast Ship Performance in Calm Water via Experiments: The Impact of Loading Variation and Longitudinal Centre of Gravity Shift on Scale Effects in Resistance Model Tests  
  by Mohsen Mollaei Kandalous, Parviz Ghadimi 
  Abstract: High-speed vessels are complex and costly, requiring careful pre-production design. Scaled towing-tank tests are practical, but Reynolds number similarity cannot be achieved due to carriage speed limits, so Froude number similarity is applied instead. This study examined two Fridsma-series models (1.5 m and 2.5 m, 20 deadrise) in calm water under two weights and three longitudinal centre of gravity (LCG) positions (32%, 34%, 36% of LOA), across a beam Froude number (FrB) range of 1.83.5, covering semi-displacement to planing regimes. Load coefficients (C) ranged from 0.5 to 0.61. Resistance, trim, rise-up, and LCG effects were measured and compared with Savitsky and ITTC57 formulations for full-scale extrapolation. Results show trim strongly influences resistance distribution, while increased load and aft LCG reduce spray resistance to ~2.5% in planing. The study highlights scale effects and the importance of optimising trim, C and LCG to improve performance.
  Keywords: Planing hull; load coefficient; resistance coefficients; scale effects; longitudinal center of gravity shift.
  DOI: 10.1504/PCFD.2026.10078655
   
  
• Multiobjective Genetic Algorithm Optimization of wind effect on Y-Plan building in the presence of interfering buildings  
  by Faiz Akram, Sujit Dalui, Saif Akram 
  Abstract: The current study aims to find the minimum force and wind pressure on different faces of the Y-plan building in the presence of two square plan-shaped buildings of the same height through the multi-objective genetic algorithm (MOGA) technique of optimisation. A hundred random sample points have been taken by varying the interfering building distances () and wind incidence angles () to generate the parametric models through CFD simulation in Ansys. Which in turn are used for random surface approximation (RSA) to construct the surrogate models for the objective functions. The steady RANS k- turbulence model and 1:300 length scale factor have been adopted for the simulation. The results from RSA and CFD are compared and several optimum points have been found through Pareto-optimal solution (POS) which indicate the minimum pressure points on the principal structure. A design engineer can pick any of these optimum points for the economical and efficient construction of the building.
  Keywords: genetic algorithm; interfering; optimisation; Pareto-optimal solution; pressure; random surface approximation; simulation.
  DOI: 10.1504/PCFD.2026.10078835
   
  
• Nonlinear Horned Lizard Optimised Stretching Sheet Framework in Non-Newtonian Fluids  
  by Muniratnamma M, Chandra Shekara G 
  Abstract: Predicting wind pressure is essential for the structural integrity of tall buildings. This study investigates wind interference on a stationary principal building caused by an interfering building oriented from 0 to 180Using open field operation and manipulation with a steady Reynolds-averaged Navier-Stokes standard k- turbulence model, wind force and pressure coefficients are evaluated. Results reveal a 1.53
  Keywords: Horned lizard optimization; Non-Newtonian Fluid; Power fluid order; Eyring–Powell fluid.
  DOI: 10.1504/PCFD.2026.10078880
   
  
• Wind Interference Study on Tall Buildings: Hybrid CFD-ML Approach for Variable Interfering Building Orientation  
  by Krishan Dutt Yadav, Bharat Singh Chauhan 
  Abstract: Vehicular ad hoc networks (VANETs) offer benefits for intelligent transportation systems but face challenges in rural areas. Space-air-ground integrated networks (SAGINs), satellite-based networks, can provide connectivity in these areas. Integrating VANETs and SAGINs can revolutionise transportation and communication. A key challenge is handover, the seamless transition between satellite coverage zones. This paper proposes a low-cost handover communication mechanism to address this challenge. This paper rigorously evaluates the security of our proposed handover protocol and demonstrates that our scheme outperforms existing methods. The proposed protocol outperforms existing handover authentication schemes, achieving an approximate 22.7% reduction in authentication delay and a 26.3% decrease in signalling cost. In essence, this work paves the way for seamless and secure communication in remote areas by bridging the gap between terrestrial and satellite networks, opening doors for improved transportation, communication, and overall quality of life for rural communities.
  Keywords: BLWT experimentation; OpenFOAM; Tall buildings; Wind interference; relative orientation; ML and DL regressions.
  DOI: 10.1504/PCFD.2026.10078881
   
  
• Numerical Analysis of Transient Behaviour of Liquid Ring Vacuum Pump during Start-Up Phase  
  by Abhishek Kumar, Mohammad Danish, Saurabh Jyoti Sarma 
  Abstract: During the startup phase of the liquid ring vacuum pump (LRVP), highly transient multiphase interactions, bubble dynamics, and pressure fluctuations create severe flow instabilities. These pressure fluctuations, along with inertial torque, lead to deformation of the impeller blade and even failure of the motor. In the present study, the start-up mechanism of the LRV pump is numerically investigated using RNG k-? turbulence model. The suction pressure and the impeller torque are recorded during the start-up from t/T=0-5, where T represents the time required to complete one revolution. The maximum initial torque at t/T = 0.25 is 1785 N-m, which decreases to nearly 120 N-m at t/T = 5. The sealing liquid experiences a temperature rise during each impeller rotation, which in turn influences the pump’s overall performance. After the simulation reaches a steady state, the obtained vacuum pressure and efficiency values are compared with experimental data reported in published literature.
  Keywords: Liquid Ring Vacuum Pump; Multiphase Flow; Turbulent Flow; RNG k-?; Startup phase.
  DOI: 10.1504/PCFD.2026.10079070
   
  
• Numerical studies on effect of the channel width in PEM fuel cells with Leaf channel flow fields  
  by Nageswar Bhukya, Yeswanth Yadav Bondada, Naga Srinivasulu G 
  Abstract: Flow field configuration is one of the important factors influencing the proton exchange membrane fuel cell (PEMFC) performance. Current study aims to ameliorate fuel cell performance, water management, and pressure drop across channels. To assess their impact on PEMFC performance, four distinct types of channel widths for leaf design flow channel were chosen. The ANSYS FLUENT software was used for numerical simulation of three dimensional PEMFC models. Under same temperature and pressure, the leaf channel with four distinct types of channel widths (0.5 mm, 1 mm, 1.5 mm and 2 mm) were compared. The simulation results revealed that the model with 0.5 mm channel width achieved highest current density of 1.33 A/cm2 and peak power density of 0.532 W/cm2 at 0.4 V, outperforming the wider channels by up to 15.6%. These findings highlight that optimised channel width can significantly enhance fuel cell performance through improved reactant distribution and membrane hydration.
  Keywords: Proton Exchange Membrane Fuel Cell (PEMFC); ANSYS Fluent; Leaf Channel; Channel Width; Water management.
  DOI: 10.1504/PCFD.2026.10079175
   
  
• Study on the One-dimensional Fitting Model for Flow Field of Aerostatic Thrust Bearing with Air Chamber  
  by Sheng-Long Nong, Shang-Han Gao 
  Abstract: This paper establishes one-dimensional flow field models for six aerostatic thrust bearings with different cylindrical chamber radii and calculates their pressure distribution and load capacity. Comparative analysis with CFD simulations proves the validity of the proposed model. A small chamber serves as a stable pressure maintenance region for high-speed airflow and enhances the saturation effect of the gas film laminar flow, effectively raising internal pressure and boosting bearing load capacity. A proper increase in chamber radius acts as an airflow buffer, slowing the incoming flow speed and alleviating the pressure drop inside the gas film. However, excessive chamber expansion leads to shock wave reflection and refraction, and the resulting shock wake further aggravates pressure loss. This decline in pressure inevitably weakens the overall load capacity. In summary, increasing the chamber radius is not a reliable method to achieve continuous performance improvement for aerostatic thrust bearings.
  Keywords: aerostatic thrust bearing; air chamber; pressure; load capacity.
  DOI: 10.1504/PCFD.2026.10079400
   
  
• Numerical Simulation of Jet-Wall Impingement Liquid Film Dynamics: Influence of Injection Velocity and Diameter on Spreading Characteristics  
  by Louis Poudevigne, Erjun Wu, Xiaodong Chen 
  Abstract: High-pressure jet impingement forms wall-attached liquid films whose spreading and interfacial waves are not well quantified for confined geometries. We perform volume-of-fluid simulations of a liquid film spreading on a curved wall at a back pressure of 1 MPa, examining the effects of injection velocity and jet diameter. Jet diameter dominates the onset and amplification of interfacial waves, exceeding the influence of velocity. Centerline thickness evolution identifies three regimes: linear wave growth, solitary-wave-dominated dynamics, and chaotic wave interaction. The transition to strongly nonlinear and chaotic behavior is markedly more sensitive to changes in diameter than to increases in velocity. Dimensional analysis shows that lateral spreading follows a Weber-number-dependent trend that deviates from classical ambient-pressure correlations for flat surfaces, indicating that elevated gas density and wall confinement modify the scaling response. The results support the use of propulsion and film-cooling applications.
  Keywords: Liquid film; Numerical simulation; Liquid jet impingement; Spreading characteristics; Scaling law; High-pressure.
  DOI: 10.1504/PCFD.2026.10079549
   
  
• Experimental Investigation of Electrohydrodynamic Fan Airflow Characteristics for Design Optimisation  
  by Klaudia Zwoli?ska-Gl?dys, Marek Borowski, Jean Paul Cardona Murillo, Marek Ró?ycki, Marek Jaszczur 
  Abstract: Growing demand for compact, energy-efficient, and quiet airflow systems drives interest in alternatives to conventional rotary fans. This study experimentally evaluates an electrohydrodynamic (EHD) bladeless fan using a high-voltage needle emitter and grounded ring collector to generate airflow via corona discharge and ion-driven momentum transfer. A configurable needle-to-ring prototype examined the effects of electrode spacing and applied voltage on aerodynamic performance. Using Particle Image Velocimetry and hot-wire anemometry, flow fields were quantified, revealing a linear correlation between applied voltage and flow velocity. Primary acceleration occurs within the inter-electrode region, with both velocity magnitude and flow shape highly sensitive to electrode spacing. At 10 kV, peak velocities measured 33 mm downstream range from 2.0 to 3.0 m/s, with tighter spacings producing a more confined jet. These high-resolution velocity profiles benchmark computational fluid dynamics simulations and confirm EHD fans as promising candidates for thermal management in space-constrained electronic applications.
  Keywords: Electrohydrodynamics; Corona discharge; Airflow characterization; Particle Image Velocimetry; Efficiency.
  DOI: 10.1504/PCFD.2026.10079889
   
  
• Numerical investigation on head-on droplet collisions based on modified coupled level set-VOF  
  by Xiaohang Qu, Qianjian Guo, Xiaoni Qi 
  Abstract: Seawater droplet collision phenomenon exists widely in marine environments. A model is developed for the collision process of seawater droplets composed of various salts. The head-on collision of binary equal-sized seawater droplets has been investigated based on the phase interface tracing method of coupled level set-VOF with the adaptive mesh refinement. The initialisation method of phase function, the solution method of convection transport equation of the phase function, the construction and realisation method of phase interface and the method of function re-initialisation are developed. The tetradecane droplet collisions are numerically studied to validate the numerical method. The results show good agreement with experimental data from the literature. The head-on collisions of seawater droplet are first numerically investigated at various Weber numbers (from 0.5 to 200). Different collision outcomes have been observed for various parameters, such as coalescence and reflection separation. The critical Weber number of separation is obtained. The evolution of the droplet's kinetic energy, the surface energy and the dissipation energy as well as the maximum deformation for seawater droplets is also evaluated. This work contributes to a fundamental understanding of the mechanism of seawater droplet collision and the application of droplet collision models to related processes.
  Keywords: droplets collision; seawater; numerical investigation; modified coupled level set-VOF; M-CLSVOF.
  DOI: 10.1504/PCFD.2025.10075233
   
  
• Numerical investigation for the flow past a single and in-line stick-slip cylinder in a planar flow  
  by Manish Dhiman 
  Abstract: Flow past bluff bodies is a fundamental problem in fluid mechanics. Recently, the influence of confinement on such flows has gained significant attention, as nearby no-slip walls can markedly alter phenomena like flow separation and stagnation points. Concurrently, the development of 'Janus' cylinders - materials with distinct surface properties - have shown considerable promise in various applications. In this study, flow structures and hydrodynamic forces on a circular stick-slip (Janus) cylinder, centrally placed within a confined channel, are investigated at low cylinder Reynolds numbers (Re_p = 1-100) for different channel-to-cylinder diameter ratios (H/D). Comparisons are made with conventional uniform-surface (stick) cylinders. Results show that the recirculation zone enlarges with increasing H/D, and shear stress distributions indicate that separation points shift further downstream. Empirical correlations for drag, lift, and moment coefficients are proposed. Additionally, the flow over two in-line stick-slip cylinders is analysed, revealing significant alterations in streamline patterns and hydrodynamic forces.
  Keywords: stick-slip cylinders; confinement; in-line array.
  DOI: 10.1504/PCFD.2025.10075737
   
  
• Simulation of mixed convection in a modified T-shaped enclosure with an insulated vertical strip  
  by Hamza Khan, Humayoun Shahid, Yasir Nadeem Anjam, Salman Arif Cheema, Fayyaz Ahmed 
  Abstract: This study explores the influence of a centrally located insulated strip in a reverse T-shaped enclosure on fluid flow and heat transfer using the multi-relaxation-time lattice Boltzmann method (MRT-LBM). The bottom wall is uniformly heated and driven by a moving lid at velocity u = u₀, while the remaining walls are cold, except for adiabatic bottom shoulder segments with ϑT/ϑy = 0. The vertical insulated strip allows flow near the top wall, acting as a passive thermal barrier. Simulations are conducted for Grashof numbers from 10⁴-10⁶, Richardson numbers from 0.01-100, and Prandtl numbers from 0.7-7. The geometric influence is examined by varying L₁/L and L₂/L. Results include streamlines, isotherms, and local Nusselt number profiles, revealing that the strip significantly modifies convective structures and enhances heat transfer behaviour.
  Keywords: heat transfer; mixed-convection; lattice-Boltzmann-method; reverse T-shaped enclosure; multi-relaxation-time lattice.
  DOI: 10.1504/PCFD.2025.10075941
   
  
• CFD-based assessment of thermal behaviour in the drone bottom housing plate  
  by Haydar Kepekci, Muhammet Aydin Metin, Kenan Senturk 
  Abstract: This study presents a numerical analysis of the geometric and material optimisation of the drone's bottom housing plate, which plays a key role in the thermal management of UAV battery modules. Four aperture geometries (square, rectangular, circular, hexagonal) have been designed and tested with three materials (aluminium, carbon fibre, PLA). Models have been created using computer-aided design software, and thermal behaviour was evaluated through CFD simulations using a conjugate heat transfer approach. Constant heat generation from the battery was defined as 87,000 W/m³, with airflow conditions set at 1 m/s and 5 m/s. The SST k-ω turbulence model and second-order discretisation schemes have been employed for accurate predictions. Average surface temperatures of the housing plates have been compared, showing that the aluminium plate with circular geometry achieved the lowest temperatures and best thermal distribution. The results highlight the importance of geometry and material selection in improving UAV battery thermal management.
  Keywords: Unmanned aerial vehicle; battery thermal management; drone bottom housing plate; geometry optimisation; CFD; heat transfer; turbulence model; SST k-ω.
  DOI: 10.1504/PCFD.2027.10077630