Numerično modeliranje razlitja nafte v reko z uporabo mrežne Boltzmannove metode : doktorska disertacija

Maslo, Aljaž (author), Žagar, Dušan (mentor), Panjan, Jože (comentor)

Doktorska naloga obravnava uporabo mrežne Boltzmannove metode (MBM) kot alternativo Lagrangeevim in Eulerjevim metodam za modeliranje razlitij nafte v rekah. Ker MBM uporablja preprostejše diferencialne enačbe lahko z njeno uporabo učinkoviteje modeliramo prenos razlite nafte kakor z obstoječimi modeli. Novo razviti model MBM je splošen in uporaben za simulacije razlitij nafte na rekah in morju, kar smo potrdili z njegovo validacijo na obeh primerih. Dosegli smo zelo dobro ujemanje rezultatov pri simulaciji razlitja pred libanonsko obalo leta 2006 in ob primerjavi modelnih rezultatov MBM z modelom Nafta3D na hipotetičnem razlitju na reki Savi. Po dokazu zanesljivosti modela MBM smo preverili še učinkovitost njegovega delovanja. Testiranje je potekalo dveh korakih, v prvem smo z več kot 1400 različnimi simulacijami preverili učinkovitost metod brez vpliva oblike računskega območja na računski čas, pri čemer je bil model MBM v povprečju osemkrat hitrejši od obstoječih modelov ob doseganju enake natančnosti. V drugem koraku smo pokazali, da oblika računskega območja nima večjega vpliva na povečanje njegovega računskega časa. S tem smo potrdili, da je novi model MBM vsaj enakovreden obstoječim modelom za simulacije prenosa nafte v naravnem okolju. V realnem primeru razlitja nafte lahko z uporabo MBM znatno prihranimo na računskem času. Novi model se lahko zato izkaže kot dragoceno orodje pri preprečevanju ali omilitvi posledic razlitij nafte in ga zato lahko priporočimo tudi ustreznim službam za uporabo v praksi.

• Language: Slovenian
• Keywords: grajeno okolje, gradbeništvo, disertacije, mrežna Boltzmannova metoda, učinkovitost, modeliranje razlitja nafte, Hermitovi polinomi, kinetična teorija, Nafta3D, TOP12
• Work type: Doctoral dissertation
• Typology: 2.08 - Doctoral Dissertation
• Organization: FGG - Faculty of Civil and Geodetic Engineering
• Place of publishing: Ljubljana
• Publisher: [A. Maslo]
• Year: 2015
• Number of pages: XX, 136 str.
• PID: 20.500.12556/RUL-32532
• UDC: 532:519.61/.64:551.464.3:665.61:504.1:(043.3)
• COBISS.SI-ID: 6985569
• Publication date in RUL: 10.07.2015

MASLO, Aljaž, 2015, Numerično modeliranje razlitja nafte v reko z uporabo mrežne Boltzmannove metode : doktorska disertacija [online]. Doctoral dissertation. Ljubljana : A. Maslo. [Accessed 11 April 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=32532

Secondary language

• Language: English
• Title: Numerical modelling of oil spills in rivers using lattice Boltzmann method : doctoral thesis

Abstract

We tested the adequacy of using the lattice Boltzmann method (LBM) as an alternative to Eulerian or Lagrangian methods in river oil spill modelling. By using simpler sets of partial differential equations, derived with the discretisation of the Boltzmann Bhatnagar-Gross-Krook (BGK) equation, the LBM model is able to achieve higher computational efficiency than the established models. The newly developed LBM model is a general model that can be used to simulate the transport of oil in rivers and seas. It was validated on the 2006 Lebanon oil spill case using a two-dimensional two-relaxation-time D2Q9 model; and by comparing three-dimensional D3Q7 Zhou model results to the results of the Nafta3D model for a river oil spill. After the reliability of the results of the LBM model was confirmed, the next step was to determine whether the LBM model is equivalent to or possibly, as hypothesised, better than existing models. The efficiency of the model was tested in two phases. In the first phase, more than 1400 different simulations were carried out to assess the efficiency of the methods without taking into account the effect of the calculation domain on the calculation time. The D2Q9 LBM model was on average eight times faster than existing models while maintaining the same level of accuracy. In the second phase, we discovered that the shape of the calculation domain does not have any significant impact on the calculation time, thus fully confirming our initial hypothesis. In an actual oil spill event, the use of the LBM can result in significantly shorter calculation times, which can contribute significantly to reducing the consequences of pollution. The new model has proved to be a valuable tool in this area and can therefore be recommended for use in real oil spill events.

• Keywords: built environment, civil engineering, thesis, lattice Boltzmann method, efficiency, oil spill modelling, Hermite polynomials, kinetic theory, Nafta3D, TOP12