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RISS 인기검색어
- 검색키워드
- 저자 : Hrvoje Jasak (검색결과 6 건)
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CFD validation and grid sensitivity studies of full scale ship self propulsion
Hrvoje Jasak,Vuko Vukcevic,Inno Gatin,Igor Lalovic 대한조선학회 2019 International Journal of Naval Architecture and Oc Vol.11 No.1
A comparison between sea trial measurements and fullescale CFD results is presented for two self epropelled ships. Two ships considered in the present study are: a general cargo carrier at Froude number Fn ¼ 0:182 and a car carrier at Fn ¼ 0:254. For the general cargo carrier, the propeller rotation rate is fixed and the achieved speed and trim are compared to sea trials, while for the car carrier, the propeller rotation rate is adjusted to achieve the 80% MCR. In addition, three grids are used for each ship in order to assess the grid refinement sensitivity. All simulations are performed using the Naval Hydro pack based on foam-extend, a community driven fork of the OpenFOAM software. The results demonstrate the possibility of using highefidelity numerical methods to directly calculate ship scale flow characteristics, including the effects of free surface, nonelinearity, turbulence and the interaction between propeller, hull and the flow field.
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CFD validation and grid sensitivity studies of full scale ship self propulsion
Jasak, Hrvoje,Vukcevic, Vuko,Gatin, Inno,Lalovic, Igor The Society of Naval Architects of Korea 2019 International Journal of Naval Architecture and Oc Vol.11 No.1
A comparison between sea trial measurements and full-scale CFD results is presented for two self-propelled ships. Two ships considered in the present study are: a general cargo carrier at Froude number $F_n=0:182$ and a car carrier at $F_n=0:254$. For the general cargo carrier, the propeller rotation rate is fixed and the achieved speed and trim are compared to sea trials, while for the car carrier, the propeller rotation rate is adjusted to achieve the 80% MCR. In addition, three grids are used for each ship in order to assess the grid refinement sensitivity. All simulations are performed using the Naval Hydro pack based on foam-extend, a community driven fork of the OpenFOAM software. The results demonstrate the possibility of using high-fidelity numerical methods to directly calculate ship scale flow characteristics, including the effects of free surface, non-linearity, turbulence and the interaction between propeller, hull and the flow field.
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OpenFOAM : Open source CFD in research and industry
Jasak, Hrvoje The Society of Naval Architects of Korea 2009 International Journal of Naval Architecture and Oc Vol.1 No.2
The current focus of development in industrial Computational Fluid Dynamics (CFD) is integration of CFD into Computer-Aided product development, geometrical optimisation, robust design and similar. On the other hand, in CFD research aims to extend the boundaries of practical engineering use in "non-traditional" areas. Requirements of computational flexibility and code integration are contradictory: a change of coding paradigm, with object orientation, library components, equation mimicking is proposed as a way forward. This paper describes OpenFOAM, a C++ object oriented library for Computational Continuum Mechanics (CCM) developed by the author. Efficient and flexible implementation of complex physical models is achieved by mimicking the form of partial differential equation in software, with code functionality provided in library form. Open Source deployment and development model allows the user to achieve desired versatility in physical modeling without the sacrifice of complex geometry support and execution efficiency.
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OpenFOAM : Open source CFD in research and industry
Hrvoje Jasak 대한조선학회 2009 International Journal of Naval Architecture and Oc Vol.1 No.2
The current focus of development in industrial Computational Fluid Dynamics (CFD) is integration of CFD into Computer-Aided product development, geometrical optimisation, robust design and similar. On the other hand, in CFD research aims to extend the boundaries of practical engineering use in "non-traditional" areas. Requirements of computational flexibility and code integration are contradictory: a change of coding paradigm, with object orientation, library components, equation mimicking is proposed as a way forward. This paper describes OpenFOAM, a C++ object oriented library for Computational Continuum Mechanics (CCM) developed by the author. Efficient and flexible implementation of complex physical models is achieved by mimicking the form of partial differential equation in software, with code functionality provided in library form. Open Source deployment and development model allows the user to achieve desired versatility in physical modeling without the sacrifice of complex geometry support and execution efficiency.
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Numerical simulations of hydrodynamic loads and structural responses of a Pre-Swirl Stator
Bakica Andro,Vladimir Nikola,Jasak Hrvoje,김은수 대한조선학회 2021 International Journal of Naval Architecture and Oc Vol.13 No.1
This paper investigates the effect of different flow models on the Pre-Swirl-Stator structural response from the perspective of a non-existing unified design procedure. Due to viscous effects near the propeller plane, the hydrodynamic solution is calculated by Computational Fluid Dynamics (CFD). Three different models are analysed: without the propeller, with the actuator disk and with the propeller. The main intention of this paper is to clarify the effects of the propeller model on the structural stresses in calmwater and waves which include the ship motion. CFD simulations are performed by means of OpenFOAM, while the structural response is calculated by means of the Finite Element Method (FEM) solver NASTRAN. Calm-water results have shown the inclusion of the propeller necessary from the design perspective, while the wave simulations have shown negligible propeller influence on the resulting stresses arising from the ship motions.
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CFD verification and validation of green sea loads
Gatin, Inno,Vukč,ević,, Vuko,Jasak, Hrvoje,Seo, Jeonghwa,Rhee, Shin Hyung Elsevier 2018 Ocean engineering Vol.148 No.-
<P><B>Abstract</B></P> <P>An extensive verification and validation for green sea load simulations is presented. The calculations are performed using the Naval Hydro pack, a library based on foam–extend, which is an open source Computational Fluid Dynamics software. The geometric Volume of Fluid method is used for interface advection, while the Ghost Fluid Method is employed to discretise the free surface boundary conditions at the interface. Pressure measured at the deck of a fixed structure is compared to experimental data for nine regular waves. Verification is performed using four refinement levels in order to reliably assess numerical uncertainties. A detailed uncertainty analysis comprises both numerical and experimental data. Comparable uncertainties are exhibited in simulations and experiments, with good agreement of results.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Verification and validation of the CFD code for green sea loads. </LI> <LI> Detailed verification using least squares fit method for unsteady flows. </LI> <LI> Results validated against experimental measurements. </LI> <LI> Paper shows the state of a modern CFD code for green sea assessment. </LI> </UL> </P>
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