Flow over rough surfaces, and conjugate heat transfer, in engineering applications
Doktorsavhandling, 2018

This thesis focuses on two important topics in the field of fluid mechanics and heat transfer that were treated separately. On the one hand, the flow over rough surfaces, which is not yet completely understood, despite of the fact that it has an important implication in many engineering applications, especially in the naval industry for ships and boats because the friction drag caused by fouling, antifouling coatings and roughness in general impacts the fuel consumption and toxic emissions to the atmosphere. In this thesis, new ways to measure and predict the friction drag of rough surfaces are presented, using both numerical simulations and experimental techniques.

On the other hand, conjugate heat transfer processes are also important in many applications, but a very relevant one is the electric generators for hydropower, since there is a current need of increasing the efficiency of these machines, which depends a lot on how they are cooled and therefore, on the rate at which the heat that is generated during their operation is dissipated (transferred to the cooling fluid). In this thesis, an experimental method for studying the heat transfer in these machines is presented and validated. Also, new correlations to improve the design phase of the electric generators are also evaluated.

Skin-Friction Drag

Naphthalene Sublimation Tecnhique



Rotating Disk

stator channel


convective heat transfer

Antifouling paint

electric generator

Impinging Jet

Ship Hull

Roughness Function

HC3, lecture hall
Opponent: Prof. Nikil Kapur, University of Leeds


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Chalmers, Mekanik och maritima vetenskaper, Strömningslära

Submicron Resolution Long-Distance Micro-PIV Measurements in a Rough-Wall Boundary Layer

The 18th International Symposia on Applications of Laser Techniques to Fluid Mechanics,; (2016)

Paper i proceeding

Traditional energy sources are running out. Current research in engineering is, to a great extend, moving towards how to modify existing applications to make them more energy efficient. With this in mind, work has been performed in the fields of fluid mechanics and conjugate heat transfer, in two different projects. The results of such work is presented in this thesis.

In the field of fluid mechanics, studies have been carried out in order to contribute to the current knowledge of the drag caused by the flow over any arbitrary rough surface, since this is not yet fully understood. The fuel consumption and emissions are affected in great manner by the drag that is caused by a rough hull in the naval industry, for example. Experiments and numerical simulations using commercial CFD codes are presented for this

In the field of heat transfer, a current application in which modifications of the existing designs could lead to energy efficiency is the electric generator used for hydro-power. The efficiency of these machines is greatly affected by the dissipation of the heat that is generated during their operation. This efficiency can be improved if the manufactures of electric generators are provided with more accurate tools for determining the required
cooling system during their operation. This is only possible if the heat transfer processes in these machines are understood. Current work
presents CFD simulations and experiments to contribute to the better understanding of how heat transfer occurs during the operation of electric generators. Experiments and numerical simulations using an open source code are presented.



Teknisk mekanik


Marin teknik



Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4519


Chalmers tekniska högskola

HC3, lecture hall

Opponent: Prof. Nikil Kapur, University of Leeds

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