数值模拟湍流热传递过粗糙表面博士研究员（科研助理）

Description of the workplace The doctoral student will be employed at the Department of Energy Sciences, Faculty of Engineering (LTH), Lund University, and will be part of the Division of Heat Transfer. The research environment conducts research in fluid mechanics, heat transfer and computational fluid dynamics, with particular emphasis on the numerical modelling and simulation of turbulent flows and engineering applications. The doctoral student will work in a research environment combining fundamental research with applications of direct relevance to industry. The project will be carried out in close collaboration with Siemens Energy AB, Ericsson AB, TRATON AB and RISE. This provides an opportunity to work at the interface between fundamental research, advanced numerical methods and industrially relevant problems. The doctoral student will have access to expertise in Computational Fluid Dynamics (CFD), turbulence, heat transfer, numerical methods and high-performance computing. The work will involve extensive use of high-performance computing resources, including both GPU- and CPU-based computing platforms. Being a doctoral student As a doctoral student, you are both admitted as a student and employed at Lund University. As a doctoral student, you will be trained in a scientific approach. In short, you will be trained to think critically and analytically, to solve problems independently using the right methods, and to develop an awareness of research ethics. In addition, you will have the opportunity to work on projects, to develop your leadership and pedagogical skills. Throughout your studies, you will be guided by supervisors. Doctoral studies end with a thesis and a doctoral degree. More about being a doctoral student at LTH on lth.se . Subject and project description Surface roughness has a significant influence on turbulent flow, wall friction and heat transfer in many engineering systems. Understanding and predicting these effects is important in a wide range of applications, including energy systems, thermal management and transport applications. Despite its practical importance, accurately predicting turbulent heat transfer over realistic rough surfaces remains challenging, particularly when the properties of the working fluid and the relative thicknesses of the momentum and thermal boundary layers vary. The aim of this doctoral project is to develop a deeper physical understanding of the interaction between surface roughness, turbulence and heat transfer , and to translate this understanding into improved engineering models. The research will primarily use high-fidelity numerical simulations, including Direct Numerical Simulation (DNS) and Large Eddy Simulation (LES) . Different CFD codes will be employed depending on the problem and required level of fidelity, including OpenFOAM, CaNS and nekRS . The simulations will make extensive use of modern high-performance computing resources based on both GPUs and CPUs . The project will investigate how surface roughness influences turbulent flow and heat transfer for different fluids and thermal conditions. Particular attention will be given to the interaction between roughness geometry, turbulent structures, and the momentum and thermal boundary layers, including conditions in which the relative thicknesses of the thermal and momentum boundary layers differ. The high-fidelity simulation data will be used to identify relevant physical mechanisms and scaling relations and to support the development of reduced-order and engineering models for rough-surface heat transfer , including improved models and correlations suitable for Reynolds-Averaged Navier–Stokes (RANS) simulations. The overall objective is to establish a connection between fundamental turbulence physics, high-fidelity numerical simulations and computational models that can be applied to engineering design. The project will be conducted in close collaboration with Siemens Energy AB, Ericsson AB, TRATON AB and RISE , providing opportunities for scientific exchange and interaction with researchers and engineers working on industrial applications of turbulent flow and heat transfer. Work duties You will primarily devote yourself to your doctoral studies, which include participation in research projects as well as third-cycle courses, seminars and scientific conferences. A central part of your work will be to perform and analyse high-fidelity numerical simulations of turbulent flow and heat transfer over rough surfaces. You will use CFD and high-performance computing frameworks, which may include OpenFOAM, CaNS and nekRS, on CPU- and GPU-based systems. Applicants should already have experience with comparable simulation tools and High Performance Computing (HPC) systems; familiarity with the specific codes used in the project is an advantage. The work duties include: • Performing DNS and LES of turbulent flow and heat transfer over rough surfaces using OpenFOAM, CaNS, nekRS or comparable CFD and scientific-computing frameworks. • Setting up, running, validating and analysing simulations on GPU- and CPU-based high-performance computing systems . • Investigating the influence of surface roughness geometry and characteristics on turbulent momentum and heat transfer. • Investigating the effects of fluid properties and thermal conditions , including different relationships between momentum and thermal boundary-layer thicknesses. • Processing, analysing and visualising large datasets and identifying physical mechanisms and developing scaling relations from DNS and LES data. • Developing reduced-order models, correlations and improved RANS modelling approaches for turbulent heat transfer over rough surfaces. • Assessing and validating the developed models against high-fidelity numerical data and, where available, experimental data. • Collaborating with researchers at Lund University and with the project's industrial and research partners. • Presenting research results at project meetings, scientific conferences and international workshops. • Writing scientific articles for publication in international peer-reviewed journals and contributing to the doctoral thesis.

The work may involve travel within Sweden and internationally for project meetings, visits to research and industrial partners, conferences and research collaborations. The duties may also include participation in teaching and other departmental work, however to a maximum of 20% of working hours. Admission requirements A person meets the general admission requirements for third-cycle courses and study programmes if the applicant: • has been awarded a second-cycle qualification, or • has satisfied the requirements for courses comprising at least 240 credits of which at least 60 credits were awarded in the second cycle, or • has acquired substantially equivalent knowledge in some other way in Sweden or abroad.

Additional requirements In order to complete the doctoral programme in question, the following are also required: • A Master’s degree, or equivalent qualification, in mechanical engineering, engineering physics, aerospace engineering, energy engineering, applied mathematics, computational science, or another subject relevant to the project. • Good knowledge of fluid mechanics, CFD, and turbulent flows, and relevant knowledge of heat transfer. • A substantial research project or thesis in CFD, turbulence, heat transfer, or a closely related field. • Demonstrated ability to independently set up, run, troubleshoot, validate and analyse numerical simulations. This should be supported by research experience, rather than coursework alone. • Scientific programming experience in a relevant language, such as C/C++, Fortran and Python or Matlab. • Practical experience running computational simulations on HPC systems. • Ability to plan and carry out research tasks with limited day-to-day supervision, analyse results critically and communicate findings clearly. • Very good knowledge of English, spoken and written.

Other qualifications For the doctoral programme in question, the following are considered meriting: • Experience with DNS or LES, wall-bounded turbulence, turbulent heat transfer, surface roughness or convective heat transfer. • Experience with a CFD or high-fidelity simulation framework, such as OpenFOAM, CaNS, nekRS or a comparable research code. • Experience with parallel computing or GPU-accelerated scientific computing. • Knowledge of RANS, wall modelling or thermal turbulence modelling. • Research experience beyond the Master’s thesis, such as work as a research assistant or research engineer. • Experience presenting or publishing research results or collaborating with industry.

Applicants are not expected to have experience with every code used in the project. However, they should have demonstrated the ability to carry out computational research independently using a comparable CFD or scientific-computing framework. They are expected to contribute from an early stage, building on existing experience in numerical simulation and HPC. We offer Lund University is a public authority which means that employees get particular benefits, generous annual leave and an advantageous occupational pension scheme. More about working at Lund University on lu.se . About the employment The employment is a fixed-term employment at full time, starting as soon as possible. Third cycle studies at LTH consist of full-time studies for 4 years. In the case of teaching and other departmental duties, the employment is extended accordingly. Doctoral studentships are regulated in the Higher Education Ordinance (1993:100), chapter 5, 1-7 §§. More about terms of employment for doctoral students on Lund University’s Staffpages . Other The doctoral student will be expected to interact regularly with the project's academic and industrial partners. The position may therefore include visits to partner organisations and participation in project meetings, workshops and conferences in Sweden and abroad. How to apply Applications shall be written in English and include: • CV and cover letter stating why you are interested in the doctoral programme and this particular research project, and explaining how your educational background, research experience and interests relate to CFD, turbulence and heat transfer. • Copies of issued study certificates and/or awarded degree certificates. These must confirm that you meet the general and specific admission requirements for the doctoral programme and demonstrate that you have the subject knowledge required for the doctoral research project. • Degree transcripts showing completed courses and grades. • A copy of the Master's thesis or, if the thesis has not yet been completed, a summary of the ongoing thesis work and its expected completion date. • Other documents you wish to be considered, such as scientific publications, technical reports, conference contributions, letters of recommendation or other material demonstrating relevant research experience. • Contact information for at least two references who may be contacted during the recruitment process.

We welcome your application.