KTH is the largest technical university in Sweden. Education and research cover a broad spectrum within natural sciences and engineering, as well as architecture, industrial engineering and manage-ment, urban planning, work science and environmental engineering. There are circa 12,000 full-year undergraduate students, 1,400 postgraduate students and 3,100 employees.
The School of Engineering Sciences carries out a wide range of research at the international front line, from fundamental disciplines such as physics and mathematics, to engineering mechanics with applications such as aeronautics and vehicle engineering. We also offer University degree programs in engineering Physics, Vehicle engineering, Engineering and Education, and Open Entrance, as well as a number of International Masters Programmes.
The following three doctoral positions in Mechanics are open for applicants.
Doctoral student in Fluid Mechanics
The applicant should have an MSc degree in Fluid Mechanics or related fields.
As the transition from laminar to turbulent flow is associated with an increase of friction drag, re-cent requirements on significant reduction of CO2 and NOx have resulted in an increased interest for laminar aircraft design. Since laminar-turbulent transition in the boundary-layer lows is usually caused by breakdown of small unstable perturbations, the flow control methods for delay of transition aim at reducing the growth rate of these perturbations. An improvement of the capability to predict the laminar-turbulent transition and thereby a more accurate prediction of aircraft performance requires a better understanding of generation of perturbations in the boundary layer flows.
The aim of this project is to use advance numerical simulation tools as well as to further develop the existing analytical models to investigate and understand the receptivity process, i.e. process of generation of perturbations in the boundary layer flows caused by e.g. free-stream turbulence or surface roughness elements.
This project is a part of a bigger European research project (including several major European universities, aircraft manufacturers and aeronautic research institutes) with aim of improving the receptivity and transition-prediction methods.
The PhD student will be employed at the department of Mechanics.
Contact:
Ardeshir Hanifi, Adj. Prof.
Phone: + 8 790 84 82
eMail: hanifi@kth.se
Doctoral student in Aeroacoustics/Fluid Mechanics
The applicant should have an MSc degree related to Aeroacoustics or Fluid Mechanics. Experience of numerical simulations is a merit.
In pipes that are part of different gas transport systems, ranging from ventilation systems and exhaust systems to pipe lines, it is of importance to reduce the drag in order to minimize energy consumption and at the same time design for acoustically quiet properties. To perform such an optimization, an increased understanding of the connection between flow and the acoustic waves is crucial. The aim of this project is to investigate the effects of pulsating flows, such as acoustic fields, on the character of channel and pipe flows. An aspect is the possibility to use acoustic forcing as a mean of flow control for drag reduction. The analyses will be based on numerical tools of different complexity based on the nature of the flow field to be investigated. In addition, analytical models will support the analysis.
The PhD student will be employed at the Marcus Wallenberg Laboratory for Sound and Vibration Research (MWL) located at KTH Aeronautical and Vehicle Engineering, in strong cooperation with KTH Mechanics.
Contact:
Susann Boij, Dr.
Phone: + 8 790 91 88
eMail:sboij@.kth.se
Doctoral student in High-Performance Computing
The applicant should have an MSc degree in either Computer Science (focus on High-Performance Computing), Numerical Analysis/Applied Math or Fluid Mechanics (with focus on numerical simulations).
The numerical simulation of turbulent flows is a very active area of research in fluid mechanics. Due to the inherent nonlinear characteristics of the governing flow equations, a high-fidelity simulation of turbulence, in particular close to solid walls, requires a large number of grid points (reaching up to several 10 billions). This necessitates the use of highly parallel algorithms (MPI/OpenMP) and large computer systems (e.g. the KTH Clusters Ekman with 10000 cores, or even larger systems internationally). KTH Mechanics is very active in the field of large-scale simulations of turbulence, both in canonical (isotropic turbulence or channel flow) but also more complex geometries (e.g. diffuser flow).
Over the last years, more complex physical phenomena could be incorporated in simulations, e.g. flows with multiple phases: Think for example of water flowing in a pipe system with diluted small sand particles; or blood flow in veins with pollutants. One way to model such a case is the advection of a large number of small particles included explicitly in the flow: Each particle (there could be millions in number) is tracked individually, and its interaction with the flow is computed. Of course, various levels of accuracy are possible, e.g. fluid force on particles and vice versa, collisions between particles, and accumulation of particles at solid surfaces. From a computational point of view, this Lagrangian particle tracking is a very interesting problem in terms of efficient parallel implementation on thousands of processors.
It is the aim of the present research project to devise, implement and validate algorithms and models for such particle tracking in a massively parallel (up to 100000 processors) spectral-element code. This code allows the efficient computation of flows in moderately complex geometries such as pipe bends, diffusers etc. The main focus of the project is to extend our experience in large-scale computations, including parallel algorithms, novel computer architectures etc. Close collaboration with other developers of the code is part of the project. Although the main focus of the project is related to high-performance computing, a genuine interest in the physical aspects of turbulent flows is definitely a plus.
This PhD position will be part of the Swedish e-Science Research Centre (SeRC), in particular the Flow e-Science Community. Therefore, a broad collaboration between the various partners, including application experts at the two computer centres PDC and NSC, and the colleagues from Numerical Analysis, is envisaged. Also, the Linné FLOW Centre has a comparably large activity in multiphase flows, including several PhD projects and Postdocs.
A thorough knowledge and interest in large-scale numerical simualtions and computer implementa-tions for parallel architectures as well as physical interest in fluid mechanics is a plus. The applicant should have good control of English both written and spoken.
Contact:
Philipp Schlatter, Dr.
Phone: + 8 790 71 76
pschlatt@mech.kth.se
Employment
Form of employment: Temporary.
Start day: According to agreement.
The salary follows the direction for PhD Students.
Application deadline: 2010-10-04
Employer’s reference number: S-2010-0625
Application
Applications should be send by e-mail to:. Carolina Eneqvist, (carolina@mech.kth.se)
Please indicate reference number S-2010-0625 in the e-mail subject!
The application (in PDF) shall contain
1. a motivation letter for the present PhD position (pdf),
2. a Curriculum Vitae (pdf),
3. university diplomas and grade transcripts (pdf),
4. contact information to possible references (pdf).
