It is very important to develop efficient but still accurate and stable numerical methods for solving heat and mass transfer processes in many industrial applications. The thesis deals with an inverse heat conduction problem which is used to compute boundary conditions (temperatures, heat flux or heat transfer coefficient). Nowadays, two approaches are often used for inverse task - sequential estimation and whole domain estimation. The main goal of this work is to develop a new approach, the so-called sub-domain method, which emphasizes advantages just as reduce disadvantages of both methods mentioned above. This approach is then tested on generated prototypic data and on data from real experiments. All methods are compared with respect to accuracy of results as well as to computational efficiency.

Arterial stenosis is a disease characterized by the buildup of a waxy substance inside the artery, which is associated with certain risks. It is difficult to eval- uate the severity of the stenosis, yet the diagnosis can become more accurate using computational fluid dynamics simulations. The present thesis introduces and applies the model of hemodynamics based on the Navier-Stokes equations, implemented in the FEniCS software employing the finite element method. The main focus lies on the prescription of the boundary condition at the outlet of the computational domain. The impact of the outlet boundary condition on medically significant quantities such as the wall shear stress is analyzed in a two- dimensional benchmark case. It appears that the right choice of the boundary condition is fundamental, in particular when vortices occur and propagate across the outlet boundary. The next part of the work is dedicated to the prescrip- tion of the outflow rate in the case of more than one outlet, corresponding to an artery branching inside the computational domain. The physically meaningful flux distribution is derived introducing Murray's law and its extension. Finally, the blood flow is simulated in a three-dimensional geometry of a patient-specific carotid artery. 1

In the thesis, we study the Navier-Stokes-like and the Navier-Stokes-Fourier- like problems for the flows of homogeneous incompressible fluids. In the first part of the thesis, we introduce a new type of boundary condition for the shear stress tensor, which includes the time derivative of the velocity. Therefore, we are able to capture the dynamic response of the fluid on the boundary. As the second part of the thesis, we include the published journal article co-authored by J. Žabenský on the Navier-Stokes-Fourier-like problem formulated in the complete thermodynamic setting. In both parts, the constitutive relations are formulated implicitly with the use of maximal monotone graphs. The main result of the thesis is the existence analysis for the above mentioned problems.

The present document is the final master thesis report written by Marc PILORGET,student at SUPAERO (home institution) and KTH (Royal Institute of Technology,Exchange University). This six months internship was done at DASSAULT AVIATION(Airframe engineering department) based in Saint-Cloud, France. It spanned from the 5thof July to the 23rd of December. The thesis work aims at developing an SPH (SmoothParticle Hydrodynamics) calculation method for ditching and implementing it in the finiteelement software ELFINI® developed by DASSAULT. Ditching corresponds to a phasewhen the aeroplane is touching the water. The problematic of ditching has always beenan area of interest for DASSAULT and the whole aeronautical industry. So far, only testsand simple analytical calculations have been performed. Most of the work was carried bythe NACA (National Advisory Committee for Aeronautics) in the late 70's. However in thepast decade, a new method for fluid-structure coupling problems has been developed. Itis called SPH. The basic principle is the following: the domain is represented by means ofparticles and each particle of fluid is treated separately and submitted to the Navier-Stokes equations. The particle is influenced by the neighbouring particles with a weightfunction depending on the distance between the two particles. Particles are also placed atthe interface solid-fluid: they are called limit particles. The final purpose of this SPHmethod is to access to the structural response of an aircraft when ditching. The crucialinterest of such a method compared to methods used so far is the absence of mesh. Theanalysis of large deformation problems by the finite element method may require thecontinuous remeshing of the domain to avoid the breakdown of the calculation due toexcessive mesh distortion. When considering ditching or other large deformationsproblems, the mesh generation is a far more time-consuming task than the constructionand solution of a discrete set of equations. For DASSAULT-AVIATION, the long termobjective is to get a numerical tool able to model ditching. The SPH method is used tosolve the equations for the fluid and is coupled with a finite element method for thestructure. So far, the compressible solver for 2D geometries has been implemented.Tests are going to be performed to ensure the program’s robustness. Then theincompressible solver for 2D geometries will be studied both theoretically andnumerically.

Recent years have seen a rising interest in the use of computational fluid dynamics for investigating the hemodynamics in brain aneurysms. Hemodynamic parameters, such as wall shear stress or oscillatory shear index, are among the indicators used to detect higher risk of aneurysm rupture. This thesis describes the blood flow by generalized Navier-Stokes equations with the Navier slip boundary condition imposed on the impermeable rigid vessel wall, which is implemented by way of Nitsche's method. The influence of constitutive models and the Navier slip wall boundary conditions on the resulting blood flow and hemodynamic parameters is investigated. Five different non-Newtonian constitutive models are first compared on a 2D rectangular domain. The Carreau-Yasuda, modified Casson, and Quemada models are then employed to investigate the differences in one patient-specific aneurysm geometry obtained by CT scan. All non-Newtonian models are compared with the Newtonian model. Both steady and pulsatile simulations are performed to obtain the velocity field and hemodynamic quantities, such as wall shear stress, time-averaged wall shear stress, oscillatory shear index, and oscillatory velocity index. The results for this particular case showed that non-Newtonian models do not have a significant impact on the computed...

In this paper, we discuss the algebraic structure of bivariate C 1 cubic spline spaces over nonuniform type-2 triangulation and its subspaces with boundary conditions. The dimensions of these spaces are determined and their local support bases are constructed.

In this study, CFD simulations of a complete truck are carried out to investigate the effect of altered simulation settings at cold climatic conditions. The aim of this study is to obtain knowledge through CFD simulations performed on a selected driving condition namely at a vehicle speed of 93 kph, an ambient temperature of -20 °C and for an engine operating at 25 % load. Data from measurement carried out in a climatic wind tunnel is available and utilized as boundary conditions for the simulations.The simulations are performed under steady state conditions utilizing the commercial software STAR-CCM+. The first simulation case (reference simulation case) is constructed through java macro-scripts as per the standard VTM settings at Scania. The results from the simulations are compared with the measurement data utilizing temperature validation probes. These probes are located around the engine and measure the air temperature in the underhood engine compartment. The results from the first simulation case show that the temperature of each probe located in front of the engine and above the engine agrees well with the measured probe temperatures. But the temperature of the remaining probes show larger differences with the measured probe temperatures. To investigate the larger differences in probe temperatures, additional simulations are carried out by changing specific simulation settings. For instance, this is achieved by including thermal radiation in the physics continua. Finally, a simulation of engine load of 100 % is carried out and the results from the simulation are compared with the measurement from the same engine load as well as the results from the measurement and simulation of 25 % engine load. The results from all the simulations indicate that additional boundaryconditions and/or different methodologies need to be explored to better replicate the cold climatic conditions in the simulations.

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Wind resource assessment at California Polytechnic State University shows there is potential for wind power generation on Cal Poly land. A computational fluid dynamics model based on wind data collected from a campus maintained meteorological tower on Escuela Ranch approximately 5 miles northwest of campus suggests there are areas of Cal Poly land with an IEC Class III wind resource at a height of 80 meters above ground. In addition during the daytime when the campus uses the most energy there are large portions of land with annual average daytime wind speeds above 6.9m/s. These areas have been identified by analyzing the wind speed and directional data collected at the meteorological tower and using it to create the boundary conditions and turbulence parameters for the computer model. The model boundary conditions and turbulence parameters have been verified through comparison between data collected at Askervein hill in Scotland during the 1980’s and the results of a simulation of Askervein hill using the same model. Before constructing a wind farm for power generation, additional meteorological towers should be constructed in Poly Canyon to further confirm the wind resource prediction.