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Pri razvoju malih črpalk za pomoč levemu ventriklu pešajočega srca se v zadnjih dvajsetih letih vedno bolj uporablja računalniška dinamika tekočin, ki je ob primerni validaciji zelo uporabno orodje pri snovanju naprav. Pri doktorski disertaciji smo se osredotočili na simulacije enofaznega toka Newtonske tekočine pri konstantni temperaturi ob uporabi naprednih turbulentnih modelov družin DES in SAS, jih primerjali s široko uporabljenim SST-k? modelom in jih na koncu validirali z eksperimentom. Naloga je sestavljena iz treh delov (raziskav). Pri I. raziskavi smo izvedli preliminarni splošni preizkus na enostavni geometriji iztočne šobe, ki je bila del iniciative za razvoj numeričnih simulacij s strani Uprave ZDA za hrano in zdravila (ang. Federal Drug Administration- FDA). Pri II. raziskavi smo primerjali tokovne karakteristike ?p(Q) male komercialne črpalke HeartAssist5 z vodo in jih validirali. Pri III. raziskavi pa je bila napravljena raziskava na transparentnem preizkuševališču, izdelanem po geometriji komercialne črpalke aVAD, kjer smo numerične simulacije primerjali z merilno metodo PIV. Ugotovili smo, da se pri nominalnih delovnih pogojih naprav najbolje ujemata z eksperimentalnimi podatki napredna turbulentna modela SBES (I. in III. raziskava) in SAS (II. raziskava). SBES turbulentni model je zadnja nadgradnja modela-DES. Kriteriji, po katerih so modeli primerjani, so primerljivi računski časi izračunov na enakih numeričnih mrežah, enakem številu računskih jeder superračunalnika ter ujemanju eksperimentalnih parametrov izračunanih hitrosti in tlaka v primerjavi z numerični simulacijami. During the development process of the left ventricular assist devices (LVAD) the computational fluid dynamics (CFD) is increasingly used which is a valuable tool if validated with the experiment. In this thesis we have focused on CFD simulations of one phase, newtonian flow with a constant temperature using advanced turbulence models from DES family and SAS formulation. The comparison has been performed with widely used SST-kω model and all cases have been validated experimentally. Our task was divided into three parts (research cases). In the first case we have investigated the nozzle benchmark which was a part of a Food and Drug Administration (FDA) backed research iniciative with the goal to promote the CFD in mechanics in medicine. In the second case the Δp(Q) flow characteristics were compared in small commercial HeartAssist 5 LVAD using water as fluid. In the third case the investigation was performed on a transparent housing built on a comercial aVAD small pump, where the numerical simulations were compared with the results of Particle Image Velociometry (PIV) method. It has been concluded that the best results were obtained by SBES (I. and III. research case) and SAS turbulence models (II. research case). SBES turbulence model is the latest most updated derivative of the DES model. The criteria for the comparison was chosen like velocity, pressure difference and simulation time on the same hardware setup.

V okviru magistrskega dela je bila opravljena validacija numerične simulacije dinamičnega pojava tokovno povzročenega zvoka. Podana je bila ustrezna teoretična podlaga, sledi integralna obravnava elementa z značilnim pojavom žvižga v obliki eksperimenta, ki se je izvedel v Laboratoriju za energetske delovne stroje in tehnično akustiko na Fakulteti za strojništvo v Ljubljani. Osrednji del magistrskega dela zajema nastavitve in zagon numerične simulacije v programskem okolju Fluent. Sledi analiza vplivnih spremenljivk s pomočjo hitre Fourierjeve transformacije in slikovna obdelava animacije tokovnega polja z lastno programsko kodo. Slednje je izkazalo soodvisnost značilnih amplitud v frekvenčni domeni tokovnega polja in akustičnega pojava. Within presented thesis validation of numerical simulation regarding dynamic phenomenon of flow generated sound was performed. An appropriate theoretical basis was given, followed by the integral processing of an element with a typical phenomenon of whistle in the form of an experiment carried out in the Laboratory for pumps, compressors and technical acoustics at the Faculty of mechanical engineering in Ljubljana. The main part of the master's thesis covers the settings and start of numerical simulation in the Fluent programming environment. The analysis of influential variables is followed by the fast Fourier transformation of the sound field and the image processing of the animation of the flow field with our own program code is done. The latter showed the interdependence of the characteristic amplitudes in the frequency domain of the flow field and the acoustic phenomenon.