Fundamental Understanding of Turbulent Flow over Fluid-Saturated Complex Porous Media
Lead Research Organisation:
University of Manchester
Department Name: Mechanical Aerospace and Civil Eng
Abstract
Understanding of turbulent flow characteristics over porous media is central for unravelling the physics underlying the natural phenomena (e.g., soil evaporation, forest and urban canopies, bird feathers and river beds) as well as man-made technologies including energy storage, flow/noise control, electronics cooling, packed bed nuclear reactors and metal foam heat exchangers. In these natural and engineering applications, a step change in the fundamental understanding of turbulent flow and heat transfer in composite porous-fluid systems, which consists of a fluid-saturated porous medium and a flow passing over it, is crucial for characterisation and diagnostic analysis of such systems. Flow and thermal characteristics of the composite systems depends heavily on the interaction between the external flow, downstream wake, and the fluid flow in the porous media.
Despite the clear relevance and wide-ranging impact of this problem in nature and engineering, there is a clear lack of fundamental understanding of the flow and thermal characteristics of turbulent flow in composite porous-fluid systems, and the models that relate the exchange of the flow and thermal properties between the porous region and the external fluid passing over it. In particular, the characterisation of the velocity and thermal boundary layers over the porous media, understanding the mechanisms governing flow passage through porous media, possible flow leakage and its interaction with the wake flow, as well as their relationship with the geometric characteristics of porous media, have remained major scientific challenges. This highlights the clear need for a systematic fundamental study aimed at understanding the flow and thermal characteristics of turbulent flow over realistic porous media and the relationship between the properties of porous substrate, the flow within the porous media and the structure of turbulent flow over and past the porous region.
In this ambitious collaborative project, we combine the computational and modelling expertise at the University of Manchester and Southampton with the experimental expertise at the University of Bristol, to gain fundamental understanding of the turbulent boundary layer, flow leakage and downstream wake on the flow and thermal characteristics of fluid-saturated porous media. This will be used to establish evidence-based interface flow and thermal models, representing the exchange of flow properties between two regions through the interface. These models will then be used to develop a design tool based on the volume-averaged approach, which is a popular low-cost engineering approach for studying transport in porous media, for real-scale applications where the pore-scale analysis in computationally prohibitive.
Despite the clear relevance and wide-ranging impact of this problem in nature and engineering, there is a clear lack of fundamental understanding of the flow and thermal characteristics of turbulent flow in composite porous-fluid systems, and the models that relate the exchange of the flow and thermal properties between the porous region and the external fluid passing over it. In particular, the characterisation of the velocity and thermal boundary layers over the porous media, understanding the mechanisms governing flow passage through porous media, possible flow leakage and its interaction with the wake flow, as well as their relationship with the geometric characteristics of porous media, have remained major scientific challenges. This highlights the clear need for a systematic fundamental study aimed at understanding the flow and thermal characteristics of turbulent flow over realistic porous media and the relationship between the properties of porous substrate, the flow within the porous media and the structure of turbulent flow over and past the porous region.
In this ambitious collaborative project, we combine the computational and modelling expertise at the University of Manchester and Southampton with the experimental expertise at the University of Bristol, to gain fundamental understanding of the turbulent boundary layer, flow leakage and downstream wake on the flow and thermal characteristics of fluid-saturated porous media. This will be used to establish evidence-based interface flow and thermal models, representing the exchange of flow properties between two regions through the interface. These models will then be used to develop a design tool based on the volume-averaged approach, which is a popular low-cost engineering approach for studying transport in porous media, for real-scale applications where the pore-scale analysis in computationally prohibitive.
Organisations
- University of Manchester (Lead Research Organisation)
- University of California, Riverside (Project Partner)
- Added Scientific Ltd (Project Partner)
- EDF Energy (United Kingdom) (Project Partner)
- Arup Group (United Kingdom) (Project Partner)
- Pusan National University (Project Partner)
- BL Refrigeration & Air Conditioning Ltd (Project Partner)
Publications
Jadidi M
(2023)
On the mechanism of turbulent heat transfer in composite porous-fluid systems with finite length porous blocks: Effect of porosity and Reynolds number
in International Journal of Heat and Mass Transfer
Jalili D
(2024)
Physics-informed neural networks for heat transfer prediction in two-phase flows
in International Journal of Heat and Mass Transfer
Man A
(2023)
A divide-and-conquer machine learning approach for modeling turbulent flows
in Physics of Fluids
| Description | 4th SIG Meeting on Turbulent Heat Transfer: The Future of Thermal Engineering: A Journey with Artificial Intelligence |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Postgraduate students |
| Results and Impact | We held our 4th Special Interest Group (SIG) meeting on 27th September 2023 from 14:00-16:30. The event featured captivating presentations from both national and international speakers, who showcased the application of AI in addressing thermal engineering challenges in academia and industry. Notable contributors included representatives from NVIDIA, ANSYS, Karlsruhe, and Manchester. The meeting provided a platform for in-depth discussions and insights into the role of AI in advancing precision in thermal engineering applications, making it a valuable gathering for professionals and researchers in the field. |
| Year(s) Of Engagement Activity | 2023 |
| URL | https://fluids.ac.uk/sig/TurbHeatTrans |
| Description | Green Energy Conference, Glasgow, UK, 10-13 July, 2023: Pore-scale simulation of turbulent convective heat transfer in metal foam |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Postgraduate students |
| Results and Impact | The enhancement of heat transfer using extended surfaces has been widely applied in various engineering sectors, such as energy storage, thermal management systems, and automotive. From sophisticated aerospace applications to computer heat sinks thermal management systems are implemented. Metal Foam (MF) can be used as a thermal dissipation tool in such cases, and thus the exploration of the heat transfer mechanisms of its internal design is needed. A Computational Fluid Dynamics (CFD) model was established to investigate the thermal hydraulics of the MF at the pore-scale level. The geometry has been extracted from the micro-tomography scanning process to represent the actual stochastic shape of the MF. The MF's porosity and pore density (PPI) are 86% and 5 PPI, respectively. Varying the blockage ratio is essential to minimize the pressure drop, which is a common obstacle for a channel filled with a porous structure. However, the pressure drop reduction must not come at the expense of the heat transfer rate. Hence, three blockage ratios (BR) for a channel filled with MF were considered in this study (i.e., BR = 50%, 80%, and 100%). The enhancement of the heat transfer not only depends on the surface density of the MF but also on the flow regime, which is a critical factor. As a result, a steady-state three-dimensional Reynolds Averaged Navier-Stokes (RANS) simulation was performed for this channel, which is heated from the bottom. Conjugate heat transfer was considered to understand the blockage ratio's effect on the MF's heat transfer rate. Three Reynolds numbers (Re) based on the pore diameter were adopted in this study, and they all are within the turbulent regime of the porous media (i.e., Re = 500, 1000, and 2000). A comparison between the cases in terms of pressure drop, temperature distribution, and the Interstitial Heat Transfer Coefficient (IHTC) was accomplished. The main outcome of this study is that the BR of 80% might possess the balance between the pressure drop and heat transfer of the considered foam structure. |
| Year(s) Of Engagement Activity | 2023 |
| URL | https://www.iage-net.org/igec2023 |
| Description | Machine Learning for Fluid Flow and Heat Transfer Analysis |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Postgraduate students |
| Results and Impact | Abstract: Computational Fluid Dynamics (CFD) has revolutionized the analysis and prediction of fluid flow and heat transfer in various engineering applications. Recent advancements in machine learning (ML), particularly deep learning (DL), have sparked interest in their application to enhance CFD simulations. This talk provides an overview of deep learning in CFD, focusing on Physics-Informed Neural Networks (PINN), and addresses the challenges and pitfalls associated with their implementation. Deep learning algorithms offer promising opportunities for capturing the complexities of flow behaviour in fluid mechanics by leveraging simulation data. PINN, a combination of deep learning and the governing equations of fluid mechanics, embeds physical constraints into the neural network architecture. However, PINN faces challenges, including the requirement for labelled training data, which can be costly or time-consuming to acquire. Furthermore, satisfying local and global mass balance constraints within the network architecture can be difficult. The talk highlights the importance of addressing the pitfalls of PINN and the potential for future advancements. By combining new DL techniques with physics-based knowledge, PINN can enhance the understanding and prediction of flow behaviours in fluid mechanics, leading to improved engineering designs, optimized thermal systems, and enhanced industrial applications. |
| Year(s) Of Engagement Activity | 2023 |
| URL | https://www.sciwideonline.com/v-mae2023/ |
| Description | UK Fluids Conference 2023 (17-19th October 2023)-Glasgow: Pulsation in Turbulent Flow over Stochastic Metal Foam at the Pore Level |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Postgraduate students |
| Results and Impact | This study delves into the behaviour of turbulent flow passing over stochastic metal foam at the pore level, shedding light on the dynamic exchange of information between the flow within the porous medium and the turbulent flow above it. Employing a high-fidelity pore-scale large eddy simulation, we uncover localized pulsating jet flows within the pores, resulting in complex, time-varying patterns of flow redistribution, referred to as "flow leakage." Flow leakage denotes the preferential movement of fluid from porous regions to non-porous regions via specific pathways. Spectral analysis reveals that the primary source of this flow leakage is the low-frequency flow fluctuations within the porous medium. Furthermore, our investigation reveals an interesting phenomenon in the wake of porous ligaments at the porous-fluid interface: the occurrence of negative vertical velocity values, leading to negative flow leakage. This negative flow leakage signifies the local infiltration of fluid from non-porous regions into porous ones. Additionally, we demonstrate that information exchange takes place through both outward and inward interactions within regions exhibiting significant positive flow leakage. In areas characterized by positive mean flow leakage, there is a distinct tendency for high-momentum, streamwise-oriented flow to migrate outward from the porous medium into the non-porous regions (outward interactions). Conversely, inward interactions occur when instantaneous positive flow leakage is less than the mean value, a phenomenon associated with the pulsating nature of positive flow leakage. Finally, in regions where flow leakage is negligible, the primary modes of information exchange manifest as ejection and sweep events. During ejection, low-momentum fluid from the porous medium enters the non-porous region, while during sweep events, high-momentum fluid from the non-porous region enters the porous medium. These findings underscore the time-dependent nature of information exchange, strongly influenced by the pulsation of flow leakage from porous regions into non-porous regions. |
| Year(s) Of Engagement Activity | 2023 |
| URL | https://www.websurf.gla.ac.uk/events/conferences/ukfc2023/ |
| Description | UK Turbulence Consortium Annual Review 2023. Information transfer between porous and non-porous regions in a composite porous-fluid system |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Postgraduate students |
| Results and Impact | Abstract - The study investigates fluid flow interaction between porous and non-porous regions in a composite porous-fluid system. For this purpose, a detailed pore-scale large eddy simulation is utilized. Flow visualization shows that some portion of the fluid entering the porous blocks is pushed upwards to the porous-fluid interface and leaves the porous region; this phenomenon is called flow leakage. Spectral analysis of vertical velocity and correlation coefficients confirm the flow leakage. Below the porous interface, the magnitude of correlation coefficients exposes a strong positive correlation between vertical velocity fluctuations, revealing the upward tendency of flow in the porous region. This trend is also observed across the porous interface which confirms momentum transfer through the porous interface. Moreover, spectral analysis of vertical velocity reveals that the flow leakage has a pulsating nature and the dominant frequencies within the porous region exist in the non-porous region where the flow leakage is pronounced. This observation shows time-dependent information transfer between the porous and non-porous regions due to the pulsating flow leakage. |
| Year(s) Of Engagement Activity | 2023 |
| URL | https://link.springer.com/article/10.1007/s10494-023-00409-2 |
| Description | V-MECH2023 10-11 Now 2023: Thermal Management in Composite Porous-Fluid Systems with Metal Foam: Insights into Turbulent Flow and Heat Transfer |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Postgraduate students |
| Results and Impact | The design of thermal management systems that utilize open-cell metal foam requires a careful balance between pressure drop minimization and heat transfer enhancement. In this presentation, we propose some suggestions for the design of these types of thermal management systems to achieve design criteria and simultaneously comply with pressure drop minimization and heat transfer augmentation. we also show how blockage ratios (BRs) and Reynolds numbers (Re) can control the mechanisms governing information transfer between porous and non-porous regions. Our investigation leverages pore-scale simulations to explain exchanges of momentum and energy between these two regions. In addition, we discuss the fundamental understanding of turbulent flow and heat transfer in composite porous-fluid systems. We focus on the following topics: • Dynamics of turbulent flow and heat transfer, including the complex interactions between the porous and non-porous regions. • The unsteady nature of flow behaviors in these systems, and how this can impact their performance. • Coherent structures and their origins in these systems, and how they can be exploited to control the flow and heat transfer. • How to control the momentum and energy exchange between the porous and non-porous regions in active and passive modes. • Information transfer evolution along the porous-fluid interface, and how this can be used to characterize and predict the behavior of these systems. In this talk, we introduce a new concept, the "penetration cooling length," to analyze the pressure drop minimization and heat transfer enhancement. We discuss how to increase penetration cooling length in active and passive modes. We also present the state-of-the-art in this field and discuss the challenges and opportunities for future research. |
| Year(s) Of Engagement Activity | 2023 |
| URL | https://www.sciwideonline.com/v-mech2023/ |