Architectural design is leading us in the direction of structures with free and irregular forms. As a consequence of this the connection between the design’s intent and its fabrication represents a challenge when cre...Architectural design is leading us in the direction of structures with free and irregular forms. As a consequence of this the connection between the design’s intent and its fabrication represents a challenge when creating a support structure that is geometrically viable and which needs to possess certain aesthetic, fabricational, thermal and strength requirements. To ensure the contacts of the edges of the neighboring insulation panels along their thicknesses, the edges must be cut at different angles, which causes differences in the vertex heights and, furthermore, differences in the positions of the inner metal sheets of the insulation panels. The main goal of the presented research is the development of a post-optimization procedure, by which the minimum joint-height differences will be achieved for all the joints, taking into account all the free-form surfaces of the individual architectural design. To compensate for the residual height differences the use of spacers of different thicknesses is proposed. The paper considers the global minimization of the joint-height differences for a sample free-form architectural design that is meshed with a quad-dominant mesh.展开更多
The submarine Hydrodynamic coefficients are predicted by numerical simulations. Steady and unsteady Reynolds Averaged Navier-Stokes （RANS） simulations are carried out to numerically simulate the oblique towing exper...The submarine Hydrodynamic coefficients are predicted by numerical simulations. Steady and unsteady Reynolds Averaged Navier-Stokes （RANS） simulations are carried out to numerically simulate the oblique towing experiment and the Planar Motion Mechanism （PMM） experiment performed on the SUBOFF submarine model. The dynamic mesh method is adopted to simulate the maneuvering motions of pure heaving, pure swaying, pure pitching and pure yawing. The hydrodynamic forces and moments acting on the maneuvering submarine are obtained. Consequently, by analyzing these results, the hydrodynamic coefficients of the submarine maneuvering motions can be determined. The computational results are verified by comparison with experimental data, which show that this method can be used to estimate the hydrodynamic derivatives of a fully appended submarine.展开更多
As the maneuverability of a ship navigating close to a bank is influenced by the sidewall, the assessment of ship maneuvering stability is important. The hydrodynamic derivatives measured by the planar motion mechani...As the maneuverability of a ship navigating close to a bank is influenced by the sidewall, the assessment of ship maneuvering stability is important. The hydrodynamic derivatives measured by the planar motion mechanism （PMM） test provide a way to predict the change of ship maneuverability. This paper presents a numerical simulation of PMM model tests with variant distances to a vertical bank by using unsteady RANS equations. A hybrid dynamic mesh technique is developed to realize the mesh configuration and remeshing of dynamic PMM tests when the ship is close to the bank. The proposed method is validated by comparing numerical results with results of PMM tests in a circulating water channel. The first-order hydrodynamic derivatives of the ship are analyzed from the time history of lateral force and yaw moment according to the multiple-run simulating procedure and the variations of hydrodynamic derivatives with the ship-sidewall distance are given. The straight line stability and directional stability are also discussed and stable or unstable zone of proportional-derivative （PD） controller parameters for directional stability is shown, which can be a reference for course keeping operation when sailing near a bank.展开更多
文摘Architectural design is leading us in the direction of structures with free and irregular forms. As a consequence of this the connection between the design’s intent and its fabrication represents a challenge when creating a support structure that is geometrically viable and which needs to possess certain aesthetic, fabricational, thermal and strength requirements. To ensure the contacts of the edges of the neighboring insulation panels along their thicknesses, the edges must be cut at different angles, which causes differences in the vertex heights and, furthermore, differences in the positions of the inner metal sheets of the insulation panels. The main goal of the presented research is the development of a post-optimization procedure, by which the minimum joint-height differences will be achieved for all the joints, taking into account all the free-form surfaces of the individual architectural design. To compensate for the residual height differences the use of spacers of different thicknesses is proposed. The paper considers the global minimization of the joint-height differences for a sample free-form architectural design that is meshed with a quad-dominant mesh.
基金Project supported by the National Natural Science Foundation of China(Grant No.11272213)
文摘The submarine Hydrodynamic coefficients are predicted by numerical simulations. Steady and unsteady Reynolds Averaged Navier-Stokes （RANS） simulations are carried out to numerically simulate the oblique towing experiment and the Planar Motion Mechanism （PMM） experiment performed on the SUBOFF submarine model. The dynamic mesh method is adopted to simulate the maneuvering motions of pure heaving, pure swaying, pure pitching and pure yawing. The hydrodynamic forces and moments acting on the maneuvering submarine are obtained. Consequently, by analyzing these results, the hydrodynamic coefficients of the submarine maneuvering motions can be determined. The computational results are verified by comparison with experimental data, which show that this method can be used to estimate the hydrodynamic derivatives of a fully appended submarine.
基金supported by the National Key Basic Research Program of China(Grant No.2014CB046804)
文摘As the maneuverability of a ship navigating close to a bank is influenced by the sidewall, the assessment of ship maneuvering stability is important. The hydrodynamic derivatives measured by the planar motion mechanism （PMM） test provide a way to predict the change of ship maneuverability. This paper presents a numerical simulation of PMM model tests with variant distances to a vertical bank by using unsteady RANS equations. A hybrid dynamic mesh technique is developed to realize the mesh configuration and remeshing of dynamic PMM tests when the ship is close to the bank. The proposed method is validated by comparing numerical results with results of PMM tests in a circulating water channel. The first-order hydrodynamic derivatives of the ship are analyzed from the time history of lateral force and yaw moment according to the multiple-run simulating procedure and the variations of hydrodynamic derivatives with the ship-sidewall distance are given. The straight line stability and directional stability are also discussed and stable or unstable zone of proportional-derivative （PD） controller parameters for directional stability is shown, which can be a reference for course keeping operation when sailing near a bank.
