diplomska naloga
Jelko Gomboc (Author), Dušan Žagar (Mentor)

Abstract

Procesi pri transportu kohezivnih in nekohezivnih sedimentov se med seboj pomembno razlikujejo, saj jih pri različnih vrstah sedimenta definirajo različni parametri. Pečovnik (2014) ugotavlja, da model PCFLOW3D ne daje pravilnih rezultatov pri simulacijah na območjih s kohezivnimi sedimenti. Predlagamo enostavno enačbo, ki je primerna za računanje kohezivnih sedimentov in ne vsebuje parametrov, za katere so potrebne dodatne meritve. Enačbo smo vgradili v model PCFLOW3D in ga preizkusili. Nato smo izračunali kritične strižne napetosti za kohezivne in nekohezivne sedimente in izvedli simulacije s kombinacijami različnih tokovnih slik in parametrov valovanja. Nekohezivni sedimenti se začno privzdigovati pri višini valovanja 0,5 m, kohezivni pa šele pri 0,9 m. Tudi območja in intenziteta privzdigovanja se znatno razlikujeta. Pri danih podatkih izvira večina pridnenih strižnih napetosti iz valovanje, vetrni tokovi prispevalo le zanemarljiv delež. Vetrovi pa vplivajo na smer tokov, ter posledično na smer transporta privzdignjenega materiala. Izvedli smo tudi analizo povprečnih koncentracij privzdignjenega materiala. Rezultati so pričakovani, koncentracije se višajo z naraščanjem višine valov. Območja z večjo koncentracijo privzdignjenega sedimenta se pojavljajo na predelih z večjimi strižnimi napetostmi.

Keywords

gradbeništvo;diplomska naloga;UNI;VOI;kohezivni sedimenti;pridnene strižne napetosti;transport sedimentov;model PCFLOW3D;varovana območja;

Data

Language: Slovenian
Year of publishing:
Typology: 2.11 - Undergraduate Thesis
Organization: UL FGG - Faculty of Civil and Geodetic Engineering
Publisher: [J. Gomboc]
UDC: 004:532.5(497.4)(043.2)
COBISS: 7289697 Link will open in a new window
Views: 1977
Downloads: 742
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Other data

Secondary language: English
Secondary title: Modelling of cohesive sediment transport with the model PCFLOW3D
Secondary abstract: The processes in cohesive and non-cohesive sediment transport differ from each other significantly. Different types of sediments are defined by different parameters. Pečovnik (2014) noted that the PCFLOW3D model does not simulate transport of cohesive sediments correctly. We suggest a simple equation which is appropriate for calculating cohesive sediments and does not contain additional measured parameters. We integrated the equation in the PCFLOW3D model and tested the upgraded model. We calculated critical shear stresses for cohesive and non-cohesive sediments and performed simulations with combinations of different circulation patterns and wave parameters. Non-cohesive sediments begin to resuspend at 0.5 m high waves, while cohesive stay at the bottom until waves reach the height 0.9 m. Furthermore, the areas and the intensity of resuspension differ significantly. Using the adopted data, the majority of bed-shear stress is induced by waves, whereas wind-induced currents contribute only an insignificant part. However, the wind direction affects the direction of currents and subsequently the direction in which suspended material is transported. We also depict the depth averaged concentrations of suspended material. The results are close to our expectations; the concentrations are increasing proportionally with wave height. Areas with the highest concentration of suspended sediment occur in places with the largest shear stress.
Secondary keywords: graduation thesis;cohesive sediment;bed-shear stress;PCFLOW3D model;sediment transport;
File type: application/pdf
Type (COBISS): Bachelor thesis/paper
Thesis comment: Univ. v Ljubljani, Fak. za gradbeništvo in geodezijo
Pages: X, 26 str.
ID: 9056487