Re-examining drag reduction: the important interplay between surface and fluid properties
Lead Research Organisation:
University of Leeds
Department Name: Mechanical Engineering
Abstract
Process efficiency is at the forefront of scientific challenges due to the demand for lower global energy consumption. To achieve efficiency gains in "big-energy" processes, modifications of the chemical and physical properties are required. Chemical additives such as drag reducing agents are used to modify pipeline pressure drops, and have undoubtedly led to reductions in the overall pumping power requirements. However, the mechanism for drag reduction is not adequately understood due to a lack of attention given to the chemical-fluid interactions at the solid-liquid and liquid-liquid interfaces. The research project will consider both the colloidal science and fluid mechanics aspects of drag reduction, defining the mechanistic relationship between surface properties and bulk fluid effects. The research problem will demonstrate scalability from nano-scale surface topographies, through to slip-length modification and turbulent eddy dampening. The project will require a range of modelling techniques (to fundamentally describe the mechanism for drag reduction.
Publications
McDermott M
(2021)
An improved k - ? turbulence model for FENE-P fluids without friction velocity dependence
in International Journal of Heat and Fluid Flow
Studentship Projects
| Project Reference | Relationship | Related To | Start | End | Student Name |
|---|---|---|---|---|---|
| EP/N509681/1 | 01/10/2016 | 30/09/2021 | |||
| 1958044 | Studentship | EP/N509681/1 | 01/10/2017 | 31/08/2021 | Michael McDermott |
| Description | The project title was narrowed down to investigate and improve turbulent viscoelastic models capable of predicting drag reduction via polymer additives in turbulent channel flows (similar to flow in a pipe). Drag reduction in the context of turbulent channel flows is essentially the reduction of the friction at the wall caused by turbulent effects, typically achieved by a polymer additive. This additive acts as a 'shock-absorber' and reduces the turbulent kinetic energy near the wall and effectively increases the flow rate of the system but with the same pressure gradient without the additive (basically you get more material being transport without as much force required to move it). Computational analysis of this process is of great interest to researchers so predictions can be made were experimental setups are hard and possibly expensive to achieve. The turbulent part of the flow is modelled under an averaging process known as 'Reynolds-Averaging' which is computationally less expensive than direct methods, were every polymer-turbulent interaction is not necessary to resolve for engineering purposes. The polymer is modelled with a simple dumbell spring known as the FENE-P, in essence this spring undergoes a coil-stretch transition as the turbulence scale becomes of the same magnitude as the polymer scale (near the wall as mentioned). The work in this project develops and improves the existing computational models for RANS FENE-P fluids by making predictions on mean velocity for a range of rheological and flow conditions. New computational solvers (algorithms that run the code) are created to analyse the mathematical models developed. As part of this project, a collaboration with the leading institute in the field (University of Porto) and some of its researchers. This collaboration is ongoing and more improved turbulent viscoelastic models are due to be developed over the coming months. The output of this is a publication in progress at a high impact journal. The main focus is on the application in industrial representative geometries such as pipe bends and constrictions. |
| Exploitation Route | As this project has developed, more research questions have arisen which can be explored upon. Such include the investigation of modelling mechanical degradation of polymers under the high shearing motion of the turbulent structures, something that has very little computational models. The current research is tailored towards tackling these problems by improving and simplifying the current models available which will allow for additional features such as degradation. There are ongoing efforts to increase the current collaboration with the Portugal cohort to expand into a team of computational and experimental researchers, thus allowing future work to be conducted for potentially new PhD candidates. |
| Sectors | Chemicals,Energy,Manufacturing, including Industrial Biotechology,Other |
| Description | Turbulent viscoelatic models |
| Organisation | University of Porto |
| Country | Portugal |
| Sector | Academic/University |
| PI Contribution | I (Michael McDermott) am the lead author in a collaborative paper on an improved turbulent viscoelastic model capable of predicting drag reduction of polymer additives. The work is ongoing and the collective minds at the University of Porto and the supervisory team at the Univeristy of Leeds continues to output research with the aim of more high-impact journal publications. |
| Collaborator Contribution | The two additional supervisors/researchers at the University of Porto greatly advanced my understanding and progress within the field. This has enhanced the research ties between the University departments and also allowed for future publications to be made. |
| Impact | - High impact journal submission (in progress) |
| Start Year | 2019 |