Porous Media Approach Research Articles

Modelling the effects of particle migration and viscous dissipation on a nanofluid-cooled microchannel heat sink using porous medium approach

Modelling the effects of particle migration and viscous dissipation on a nanofluid-cooled microchannel heat sink using porous medium approach

Mathematical and Physical Description of Transport Phenomena in Heat Pipes Based on Nanofluids: A Review.

Heat pipes are highly efficient heat transfer devices relying on phase-change mechanisms, with performance heavily influenced by working fluids and operational dynamics. This review article comprehensively examines hydrodynamics and heat transfer in heat pipes, contrasting conventional working fluids with nanofluid-enhanced systems. In the present work we discuss mathematical models governing fluid flow and heat transfer, emphasizing continuum and porous media approaches for wick structures. Functional dependencies of thermophysical properties (e.g., viscosity, surface tension, thermal conductivity) are reviewed, highlighting temperature-driven correlations and nanofluid modifications. Transport mechanisms within wicks are analyzed, addressing capillary-driven flow, permeability, and challenges posed by nanoparticle integration. Fourth, interfacial phase-change conditions-evaporation and condensation-are modeled, focusing on kinetic theory and empirical correlations. Also, numerical and experimental results are synthesized to quantify performance enhancements from nanofluids, including thermal resistance reduction and capillary limit extension, while addressing inconsistencies in stability and pressure drop trade-offs. Finally, applications spanning electronics cooling, aero-space, and renewable energy systems are evaluated, underscoring nanofluids' potential to expand heat pipe usability in extreme environments. The review identifies critical gaps, such as long-term nanoparticle stability and scalability of lab-scale models, while advocating for unified frameworks to optimize nanofluid selection and wick design. This work serves as a foundational reference for researchers and engineers aiming to advance heat pipe technology through nanofluid integration, balancing theoretical rigor with practical feasibility.

Modeling bubble dynamics in rotating foam stirrer reactors: A computational fluid dynamics approach incorporating gas–solid interactions

Abstract The rotating foam stirrer reactor (RFSR) employs a donut‐shaped porous solid foam stirrer to enhance mass transfer in multiphase systems. However, the complex structure of the foam stirrer presents significant challenges for developing efficient computational models, impeding reactor optimization and scale‐up. In this work, we developed a novel bubble breakup and coalescence model based on Liao's framework, incorporating the effects of the rotating porous media. A new bubble breakup mechanism was proposed, accounting for the friction and collisions between bubbles and the struts within the foam stirrer. By integrating this model with a porous media approach, we constructed a simplified three‐dimensional computational fluid dynamics model of the RFSR. Simulation results reveal that bubble breakup within the porous medium is primarily driven by gas–solid interactions, leading to enhanced mass transfer. The model accurately predicts gas holdup and bubble size distributions, providing valuable insights for reactor design and scale‐up.

Effect of flow distribution on heat transfer in Printed Circuit Heat Exchangers using conjugate heat transfer model with a modified porous media approach

Effect of flow distribution on heat transfer in Printed Circuit Heat Exchangers using conjugate heat transfer model with a modified porous media approach

Research on the Application Effect and Parameter Optimization of 3HW36 Mountain Orchard Rail-Mounted Wind-Driven Plant Protection Equipment in Fruit Tree Canopy

This study presents a systematic optimization framework of 3HW36 Mountain Orchard Rail-Mounted Wind-Driven Plant Protection Equipment through integrated computational fluid dynamics (CFD), wind field validation, and field experiments. The CFD model demonstrated high fidelity with experimental measurements, achieving a mean absolute percentage error of 9.2% across 15 sampling points and resolving critical airflow–canopy interactions through a novel porous media approach. Field trials in Fujian citrus orchards quantified the following optimal operational parameters: 29 m/s airflow velocity (23% velocity attenuation through mid-canopy), 15° blower pitch angles (89.6% upper-middle canopy coverage), and 0.5 m/s railcar speed. The equipment’s terrain adaptability was validated through sustained post-canopy velocities (>6.4 m/s) and 62% momentum retention at 4.2 m downstream, addressing critical limitations in mountainous pesticide application. These findings establish a replicable protocol for precision canopy management, balancing agrochemical efficacy with environmental stewardship in complex orchard ecosystems.

High-Fidelity Neutronics/Thermal Hydraulics/Pebble Flow Coupling Simulation of Pebble Bed Reactor HTR-PM

Simulating pebble bed reactors with high fidelity presents significant challenges because of the intricate geometry of the randomly packed pebbles and the requirement for multiphysics coupling. This study introduces an innovative modeling framework that couples neutronics, thermal hydraulics, and pebble flow dynamics of the reactor core. The Monte Carlo (MC) code, computational fluid dynamics (CFD) method, and discrete element method (DEM) are used, utilizing the open-source codes OpenMC, OpenFOAM, and LAMMPS, respectively. The core geometry is explicitly constructed for both the MC and the DEM models, while a porous media approach is adopted for the CFD model to manage computational expenses. Enhancements have been made to OpenMC to facilitate data exchange: The core geometry is allowed to change between depletion steps to simulate pebble motion, and a temperature mesh scheme has been developed for efficient temperature distribution transfer. Validations are provided for the models and modifications implemented in this study. As a practical demonstration, a depletion simulation on a full-core model of a High-Temperature Gas-Cooled Reactor–Pebble-Bed Module (HTR-PM) is conducted, explicitly modeling 420 000 randomly packed fuel pebbles. The results reveal detailed distributions of power, temperature, and burnup, all consistent with expected physical behavior, underscoring the effectiveness of our approach.

Parametric analysis of delivered power during laser ablation for prostate cancer.

Abstract Prostate cancer is one of the most recurrent forms of cancer in men, occurring in peripheral zones. Laser ablation is an emerging non-invasive protocol for this disease, offering the possibility to preserve the prostate proper functioning. However, due to shortage of in-vivo experiments, for ethical and practical reasons, it is difficult to properly design the treatment, leading to incomplete tumor destruction and metastasis development, owed to inappropriate exposure time or laser intensity. Consequently, it is of primary importance to develop accurate models to aid and provide guidelines to surgeons, towards a treatment optimization. For these reasons, in this paper an accurate model has been developed and solved through the finite elements commercial software Comsol Multiphysics. A 2D domain, representative of the tumor inside the prostate, has been investigated, using the porous media approach. According to the Local Thermal Non-Equilibrium (LTNE) assumption, the tissue and the blood are treated as two distinct entities having different thermal properties and behavior. The laser source has been described by means of the Beer-Lambert’s law, assuming a Gaussian laser distribution. To find the optimal laser setting to achieve the maximum tumor destruction, the effect of different laser intensity, and bare fiber diameter on temperature field and thermal damage is investigated.

Calibration of a groundwater flow model in a karst aquifer using EPM approach: Case of Elhajeb-Ifrane aquifer, Morocco

Numerical models constitute a powerful tool for groundwater resources management, as they can provide information about flow path, water balance, and effects of future actions. In karst aquifers, groundwater modelling may be challenging because of the heterogeneity of the system. Indeed, karst aquifers have concentrated recharge in sinkholes and preferential flow patterns through fractures and conduits. Modellers used several approaches to simulate karst aquifers. The equivalent porous media approach was used by many researchers and showed an acceptable performance of the application of MODFLOW in regional and sub-regional aquifers. The objective of this study is to simulate the sub-regional aquifer of Elhajeb-Ifrane. The groundwater flow model was constructed using a Python package and was calibrated using the parameter estimation code. The results show a good fit between simulated and observed heads. The model reduced RMSE values to 0.49, 0.56, and 0.58 for piezometers 1098/22, 1448/22, and 1830/22, respectively. The annual water balance results show that the aquifer meanly discharges to the springs with 71.8% and 80.8% in 2016 and 2017, respectively, followed by streams with 5.9% AND 5% in 2016 and 2017, respectively, then discharges to Sais aquifers with 2.6% and 3.8% in 2016 and 2017, respectively.

Model-based optimization strategies for direct hydrogenation of carbon dioxide to dimethyl ether

Model-based optimization strategies for direct hydrogenation of carbon dioxide to dimethyl ether

Numerical simulation of vertical slot-brush fish pass: porous media approach

Numerical simulation of vertical slot-brush fish pass: porous media approach

Integrated impacts of surrounding building density and gap permeability on pollutant dispersion in four-way street networks.

Integrated impacts of surrounding building density and gap permeability on pollutant dispersion in four-way street networks.

Computational thrombosis modeling based on multiphase porous media theory for prognostic evaluation of aortic dissection after stenting

Accurately and rapidly predicting the occurrence and progression of false lumen thrombosis in patients undergoing thoracic endovascular aortic repair (TEVAR) is crucial for optimizing patient recovery. Traditional models for predicting false lumen thrombosis often lack the ability to capture phase interface changes, and their complex parameters and algorithms result in a long computation time. This study introduces a multiphase porous media approach that can accurately and rapidly predict thrombus formation in aortic dissection patients at different postoperative stages. The approach employed the Darcy–Brinkman–Stokes equation to model the interaction between the thrombotic and fluid phases and incorporated a novel porosity equation to explicitly capture phase interface dynamics. Additionally, the hemodynamic parameters associated with thrombus formation were updated to enhance the physical accuracy of the algorithm while reducing its computational complexity. Using patient-specific models derived from computed tomography angiography datasets, our algorithm demonstrated excellent predictive performance in real patients. The predicted thrombus morphology in the third and sixth months postoperatively closely matched the actual imaging data, with discrepancies in thrombus volume remaining within a ±10% range at each postoperative stage. Moreover, the algorithm significantly improved computational convergence, reducing the computation time to 30 minutes and enhancing the computational efficiency by 80% compared to traditional methods. By integrating the porous media framework, this approach offers a valuable tool for rapid clinical diagnosis and the prediction of post-TEVAR recovery.

Modeling of a Moving Reacting Carbon Char Particle Using Macropore-Resolved and Porous Media Approaches

Modeling of a Moving Reacting Carbon Char Particle Using Macropore-Resolved and Porous Media Approaches

Three-dimensional CFD modeling for hollow fiber gas separation membrane modules based on a dual porous media model

Three-dimensional CFD modeling for hollow fiber gas separation membrane modules based on a dual porous media model

Research on fluid flow and heat transfer characteristics in a three-dimensional condenser

Research on fluid flow and heat transfer characteristics in a three-dimensional condenser

Time-domain simulation of sound propagation through anisotropic porous media for room acoustic applications

Wave-based room acoustic simulations require accurate modeling of sound propagation in the presence of extended (bulk) reacting porous absorbers. The sound absorption in porous media is typically addressed by means of equivalent fluid models that provide frequency-dependent effective material parameters, such as density and bulk modulus. In the time domain, these frequency dependent properties result in the computation of convolution integrals, which is effectively handled via an auxiliary differential equations (ADE) method. In this work, we apply the time-explicit discontinuous Galerkin approach to modelling of sound propagation in anisotropic porous media (with an anisotropic equivalent fluid model) together with the ADE method. We demonstrate the importance of using the extended approach for porous media, where the sound absorption depends not only on the frequency and incident angle, but also on the travelling wave direction.

Building a physics-based virtual refrigerated container filled with fruit in ventilated packaging

We build a validated physics-based model of a refrigerated container filled with fruit in ventilated packaging. This model of a virtual container is the basis for simulations in an accompanying paper on citrus fruit shipped overseas from South Africa to Europe. The model is used to understand better how the cargo cools and when and where food quality is lost in these supply chains. We build a computational fluid dynamics model with a two-phase porous media approach that simulates the airflow in the container and the cooling process of every fruit. This container can be considered aerodynamically to be a slot-ventilated enclosure. We also model the fruit's thermally-driven quality loss. Using a two-phase porous media approach for the ventilated cargo and modeling temperature-driven fruit quality evolution are two steps forward compared to most existing physics-based refrigerated container models. We validate the porous media model implementation. We define and apply actionable metrics for every fruit inside the cargo, such as remaining shelf life upon arrival and seven-eighths cooling time.•This model can help reduce food loss and increase supply-chain resilience.•This model is an essential building block of a refrigerated container’s digital twin.•This model can support stakeholders in improving cargo temperature control and resulting fruit quality preservation.

Steady-state thermal–hydraulic analysis of an NTP reactor core based on the porous medium approach

Steady-state thermal–hydraulic analysis of an NTP reactor core based on the porous medium approach

A hybrid numerical approach for characterising airflow and temperature distribution in a ventilated pallet of heat-generating products: Application to cheese

Temperature control throughout the cold chain is of crucial importance in the preservation of the quality of cheese. As a result of cheese heat generation, both natural and forced convection need to be considered. This numerical study aimed to characterise the airflow and temperature fields within a ventilated pallet of heat-generating cheeses. An original computational fluid dynamics (CFD) hybrid approach was developed. This approach is based on a combination of a porous media approach for the contents of the boxes and a direct CFD approach for the outer cardboard walls, including vent size and position. The computational domain is limited to one pallet level. The simulations were conducted on a steady state for two upwind air velocities 0.31 m/s and 0.73 m/s and three generated heat fluxes 0.05 W, 0.15 W, and 0.3 W per product item (250 g). The model was validated by comparison with experimental results related to velocity and product temperature profiles obtained on a full-scale experimental set-up. The hybrid approach shows good accuracy while reducing the mesh size and the computational time in comparison with the direct CFD approach.

Investigation of Polyamide 12 Powder Cooling Process under Natural Convection via Porous Medium, Non-porous Medium, and Experimental Approaches

Investigation of Polyamide 12 Powder Cooling Process under Natural Convection via Porous Medium, Non-porous Medium, and Experimental Approaches