Numeričko istraživanje pojave interferencije kod katamarana

undergraduate thesis

• Title (english): Numerical investigation into the interference phenomenon for a catamaran
• Author: Ivan Tomljenović
• Mentor: Nastia Degiuli (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2022-02-03, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Shipbuilding; Hydromechanics of Floating and Maritime Structures

Abstract

U ovom radu provedeno je numeričko određivanje ukupnog otpora, trima i urona modela jednotrupnog broda i katamarana Delft 372 primjenom računalne dinamike fluida (eng. Computational Fluid Dynamics - CFD) s ciljem istraživanja utjecaja pojave interferencije na ukupni otpor katamarana. Numeričke simulacije provedene su primjenom komercijalnog programskog paketa STAR-CCM+. Matematički model temeljen je na Reynoldsovim osrednjenim Navier - Stokesovim jednadžbama (eng. Reynolds Averaged Navier - Stokes - RANS) uz primjenu k - ω SST (eng. Shear Stress Transport) modela turbulencije. Za potrebe provedbe numeričkih simulacija, primijenjen je model nestacionarnog, trodimenzijskog, viskoznog strujanja, dok je za praćenje i lociranje slobodne površine primijenjena metoda udjela fluida u volumenu (eng. Volume of fluid - VOF). Numeričko istraživanje provedeno je za tri vrijednosti Froudeovih brojeva: 0,3; 0,5; 0,75 te za dva razmaka između trupova katamarana, što je omogućilo ispitivanje utjecaja razmaka između trupova i Froudeovog broja na pojavu interferencije. Provedena je verifikacija dobivenih numeričkih rezultata te je izračunata nesigurnost mreže i vremenskog koraka pri određivanju otpora modela jednotrupnog broda i katamarana Delft 372. Nadalje, provedena je i validacija rezultata usporedbom dobivenih numeričkih rezultata s eksperimentalnim rezultatima dostupnim u literaturi. Pokazano je da je ukupni otpor katamarana veći od dvostruke vrijednosti otpora jednotrupnog broda, što ukazuje na pojavu nepovoljne interferencije pri ispitanim Froudeovim brojevima i razmacima između trupova. Konačno, pokazano je kako se računalna dinamika fluida može primijeniti kao koristan alat u istraživanju pojave interferencije.

Abstract (english)

In this study numerical assessment of the total resistance, trim, and sinkage of monohull and Delft 372 catamaran model is performed using Computational Fluid Dynamics (CFD), to investigate the impact of interference phenomenon on the total resistance of a catamaran. Numerical simulations are carried out using the commercial software package STAR-CCM+. The mathematical model is based on Reynolds Averaged Navier-Stokes (RANS) equations and k-ω SST (Shear Stress Transport) turbulence model. Unsteady three-dimensional viscous flow is numerically simulated, and the Volume of Fluid (VOF) method is utilised for tracking and locating free surface. Numerical investigations are carried out at three Froude number values: 0.3, 0.5, and 0.75 and for two demihull separations, which enabled the investigation of the impact of demihull separation and Froude number on the interference phenomenon. The verification study is performed and grid and temporal uncertainties for the prediction of the total resistance of monohull and catamaran Delft 372 model are calculated. Thereafter, the validation study is carried out by comparison of the numerically obtained results with the experimental ones available in the literature. It has been shown that the total resistance of the catamaran is higher than the double total resistance of the monohull, which demonstrates the occurrence of the detrimental interference at investigated Froude numbers and demihull separations. Finally, it has been demonstrated that Computational Fluid Dynamics can be used as a valuable tool in the investigation of interference occurrence.

• Keywords: katamaran; interferencija; računalna dinamika fluida; ukupni otpor; Reynoldsove osrednjene Navier-Stokesove jednadžbe; k-ω STT model turbulencije
• Keywords (english): catamaran; interference; Computational Fluid Dynamics; total resistance; Reynolds Averaged Navier-Stokes equations; k-ω SST turbulence model
• Language: croatian
• URN:NBN: urn:nbn:hr:235:736467
• Study programme: Title: Mechanical Engineering; specializations in: Design, Process and Energy Engineering, Production Engineering, Engineering Modelling and Computer Simulation, Marine Engineering, Industrial Engineering and Management, Materials Engineering; Course: Engineering Modelling and Computer Simulation; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/ prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka strojarstva (sveučilišni/a prvostupnik/ prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka strojarstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2022-03-02 11:00:46