Progress in Computational Fluid Dynamics, An International Journal (18 papers in press)

Regular Issues

• Investigation using a One-Way Coupled FE-Structural and FV-Hemodynamic Simulation for Identifying the Factors causing the Progression of a Saccular Aneurysm Model  
  by Suraj Raj, ANIL L.A.L. S, Anjan R. Nair 
  Abstract: Rupture risk assessment of cerebral aneurysms through computational modelling has gained importance due to the absence of objective clinical methods and challenges in experimental approaches. This study uses a one-way FSI approach with a non-Newtonian Carreau viscosity model on an idealized 3D saccular aneurysm in a curved artery to analyse key hemodynamic and structural parameters. Velocity magnitude, time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI), vorticity magnitude, von-Mises stress, and total displacement were evaluated across the cardiac cycle. A low-velocity stagnation zone was observed within the aneurysm sac. TAWSS was lower inside the sac but peaked near the distal end, where OSI values exceeded 0.2, reaching up to 0.45, indicating vulnerable regions. Vorticity and q-criterion analyses highlighted disturbed, vorticity-dominated flow regions. Maximum von Mises stress and displacement were observed near the distal regions, suggesting that shape distortions contribute significantly to aneurysm progression and rupture risk.
  Keywords: Cerebral aneurysm; rupture risk assessment; computational modelling; fluid-structure interaction (FSI); non-Newtonian; Carreau model;wall shear stress (WSS); oscillatory shear index (OSI); vorticity.
  DOI: 10.1504/PCFD.2025.10073915
   
  
• Optimisation of Drag reduction for Passive flow Control based on a Notchback MIRA model  
  by Xingren Zheng, Lingxi Deng, Zihou Yuan, Yanming Du, Hongwei Zhang 
  Abstract: This paper investigates the application of passive flow control for optimising automotive aerodynamic drag reduction, based on a notchback MIRA model. The study uses a computational fluid dynamics (CFD) simulation, a neural network prediction model and a genetic algorithm to optimise and combine the body geometry features and duckwing add-ons in a step-by-step manner. The results show that optimising the body independently reduces the drag coefficient (CD) by 12.4%, while optimising the duckwing independently reduces it by 21.109%. Combining the optimal parameters of the body and the duckwing in a composite optimisation scheme reduces the drag coefficient of the whole vehicle to 0.24509 up to 24.09% less than the original model. Flow field analysis shows that composite optimisation significantly improves rear flow field structure, effectively compresses the low-speed region and significantly reduces turbulence intensity while enhancing tail pressure recovery. This study provides an efficient optimisation strategy for the design of automotive aerodynamic drag reduction, which is important for improving vehicle energy efficiency and reducing emissions.
  Keywords: computational fluid dynamics; CFD; artificial neural network; ANN; genetic algorithm; GA; automotive aerodynamics; passive flow control; parameter optimisation.
  DOI: 10.1504/PCFD.2025.10074740
   
  
• 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 droplets 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 (Rep = 1100) 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
   
  
• 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
   
  
• Simulation of Mixed Convection in a Modified T-Shaped Enclosure with an Insulated Vertical Strip  
  by Hamza Khan, Humayoun Shahid, Yasir Nadeem, 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 $u=u_0$, while the remaining walls are cold, except for insulated bottom shoulder segments with $frac{partial T}{partial y}=0$. The vertical insulated strip allows flow near both the top and bottom walls, acting as a passive thermal barrier. Simulations are conducted for Grashof numbers from $10^4-10^6$, Richardson numbers from $0.01-100$, and Prandtl numbers from $0.7-70$. The geometric influence is examined by varying $frac{L_1}{L}$ and $frac{L_2}{L}$. 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; Mix-Convection; Reverse T-Shaped; lattice-Boltzmann method; Multi-relaxation-time.
  DOI: 10.1504/PCFD.2025.10075941
   
  
• 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
   
  
• Overset Method for Solving Moving Boundary Problems: Applications in Aeronautics  
  by Serhat ?en, Saleh Abuhanieh, ?ahin Yi?it 
  Abstract: In aeronautics, overset is a popular method to simulate moving boundary problems in computational fluid dynamics (CFD). In this study, an in-house developed overset framework is employed to investigate a set of benchmark cases involving unsteady and relative motion, including rotor hover, forward flight, and store separation scenarios. The methodology enables high-quality, body-fitted grids to move independently, enhancing numerical stability and geometric flexibility compared to traditional dynamic meshing techniques. Simulations are performed by solving the unsteady Reynolds-averaged Navier-Stokes (URANS) equations coupled with a k- SST turbulence model. For the store separation case, six-degrees of freedom (6-DOF) motion equations are integrated with the overset solver to predict the trajectory of the released body. In summary, the CFD analysis results exhibit strong agreement with the reference data, with only marginal discrepancies observed under specific conditions namely, an over-prediction of torque in hover and a minor over-estimation of yaw angular displacement for the store separation case. The findings demonstrate that the employed overset frame is reliable for modelling highly dynamic aerospace configurations involving complex moving body problems.
  Keywords: Computational Fluid dynamics; moving mesh; chimera; store separation; rotorcraft; hover.
  DOI: 10.1504/PCFD.2025.10077451
   
  
• 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 optimization 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 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 optimization; CFD; heat transfer; turbulence model; SST k-?.
  DOI: 10.1504/PCFD.2027.10077630
   
  
• Experimental and Numerical Insights on Pipe Flow Stability Mechanisms: A Unified Review  
  by Saurabh Kapoor, Siprarani Sahoo 
  Abstract: The present manuscript provides a unified review and comprehensive analysis of linear stability mechanisms in pipe flows, which are fundamental to understanding industrial applications namely, chemical reactors, nuclear cooling systems, and oil transport pipelines, along with natural processes including magma ascent, biological flows, and geothermal systems. The study synthesises key experimental and numerical investigations that validate and extend classical theoretical predictions. A broad range of numerical methodologies is reviewed, spanning traditional techniques such as the finite difference, finite element, and finite volume methods, alongside advanced approaches including spectral collocation methods, lattice Boltzmann methods, reduced-order modelling, and direct numerical simulation. Particular emphasis is placed on stability mechanisms in viscous and porous vertical pipe flows, highlighting the significant role of buoyancy-driven effects. The influence of governing parameters such as the Reynolds, Rayleigh, and Prandtl numbers on the onset of flow instabilities is systematically examined. By integrating theoretical, computational, and physical perspectives, this review offers a coherent framework for understanding convective instability in pipe flows and outlines key challenges and future research directions.
  Keywords: Pipe flow; Stability analysis; Experimental studies; Numerical insights; Unified review.
  DOI: 10.1504/PCFD.2025.10077631
   
  
• 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