Academic literature on the topic 'Quasi-rigid domains'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Contents
Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Quasi-rigid domains.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Journal articles on the topic "Quasi-rigid domains"
1
Aleksiev, T., R. Potestio, F. Pontiggia, S. Cozzini, and C. Micheletti. "PiSQRD: a web server for decomposing proteins into quasi-rigid dynamical domains." Bioinformatics 25, no. 20 (August 20, 2009): 2743–44. http://dx.doi.org/10.1093/bioinformatics/btp512.
Full text
2
Beckebanze, F., C. Brouzet, I. N. Sibgatullin, and L. R. M. Maas. "Damping of quasi-two-dimensional internal wave attractors by rigid-wall friction." Journal of Fluid Mechanics 841 (February 26, 2018): 614–35. http://dx.doi.org/10.1017/jfm.2018.107.
Full textAbstract:
The reflection of internal gravity waves at sloping boundaries leads to focusing or defocusing. In closed domains, focusing typically dominates and projects the wave energy onto ‘wave attractors’. For small-amplitude internal waves, the projection of energy onto higher wavenumbers by geometric focusing can be balanced by viscous dissipation at high wavenumbers. Contrary to what was previously suggested, viscous dissipation in interior shear layers may not be sufficient to explain the experiments on wave attractors in the classical quasi-two-dimensional trapezoidal laboratory set-ups. Applying standard boundary layer theory, we provide an elaborate description of the viscous dissipation in the interior shear layer, as well as at the rigid boundaries. Our analysis shows that even if the thin lateral Stokes boundary layers consist of no more than 1 % of the wall-to-wall distance, dissipation by lateral walls dominates at intermediate wave numbers. Our extended model for the spectrum of three-dimensional wave attractors in equilibrium closes the gap between observations and theory by Hazewinkel et al. (J. Fluid Mech., vol. 598, 2008, pp. 373–382).
3
Polles, Guido, Giuliana Indelicato, Raffaello Potestio, Paolo Cermelli, Reidun Twarock, and Cristian Micheletti. "Mechanical and Assembly Units of Viral Capsids Identified via Quasi-Rigid Domain Decomposition." PLoS Computational Biology 9, no. 11 (November 14, 2013): e1003331. http://dx.doi.org/10.1371/journal.pcbi.1003331.
Full text
4
Xu, L. M., S. Zeng, N. Guo, R. M. Lin, and D. Du. "Design and analysis of a passive damping device in a head actuator assembly." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 216, no. 3 (March 1, 2002): 353–66. http://dx.doi.org/10.1243/0954406021525061.
Full textAbstract:
It is known that a quasi-rigid-body mode (QR mode) exists in hard disk drives (HDDs) in the frequency range from 3 to 5 kHz and that it is caused by the flexibility of the pivot and the mass and structure of the head actuator assembly (HAA). This mode hinders performance improvement of the servo system in this bandwidth and thus limits the area density growth of HDDs. In this paper, a novel tuned damping device is proposed to suppress the QR mode and to reduce the residual vibration in head positioning in order to improve the servo system performance. The damping device is to be installed on the arm and hollow space within the voice coil motor (VCM) on the HDDs. The dynamic characteristics of the HAA with the tuned damping device are measured in both the frequency and the time domain and are analysed by finite element modelling (FEM). It is shown that the tuned damping device can work effectively to suppress quasi-rigid body vibration of the HAA and minimize the residual vibration in head positioning.
5
Beirão da Veiga, L., C. Canuto, R. H. Nochetto, and G. Vacca. "Equilibrium analysis of an immersed rigid leaflet by the virtual element method." Mathematical Models and Methods in Applied Sciences 31, no. 07 (June 30, 2021): 1323–72. http://dx.doi.org/10.1142/s0218202521500275.
Full textAbstract:
We study, both theoretically and numerically, the equilibrium of a hinged rigid leaflet with an attached rotational spring, immersed in a stationary incompressible fluid within a rigid channel. Through a careful investigation of the properties of the domain functional describing the angular momentum exerted by the fluid on the leaflet (which depends on both the leaflet angular position and its thickness), we identify sufficient conditions on the spring stiffness function for the existence (and uniqueness) of equilibrium positions. This study resorts to techniques from shape differential calculus. We propose a numerical technique that exploits the mesh flexibility of the Virtual Element Method (VEM). A (polygonal) computational mesh is generated by cutting a fixed background grid with the leaflet geometry, and the problem is then solved with stable VEM Stokes elements of degrees [Formula: see text] and [Formula: see text] combined with a bisection algorithm. We prove quasi-optimal error estimates and present a large array of numerical experiments to document the accuracy and robustness with respect to degenerate geometry of the proposed methodology.
6
Früh, W. G., and A. H. Nielsen. "On the origin of time-dependent behaviour in a barotropically unstable shear layer." Nonlinear Processes in Geophysics 10, no. 3 (June 30, 2003): 289–302. http://dx.doi.org/10.5194/npg-10-289-2003.
Full textAbstract:
Abstract. An experimental study on the instability of a detached Stewartson layer, using an annular, rotating tank with flat, rigid upper and lower boundaries, showed an instability to steady vortices at a critical Reynolds number, arranged in a global mode structure along the shear layer. Increasing the Reynolds number resulted in successive transitions to lower modes where time-dependent behaviour was only found for flows with three or less vortices. Previous numerical simulations of a related experiment, using a two-dimensional spectral model of the quasi-geostrophic vorticity equation incorporating Ekman forcing and viscous dissipation, suggested that the boundary conditions at the inner cylinder of the domain could significantly affect the interior flow by the generation and shedding of vorticity at this inner boundary. A comparison of the numerical results with experimental data suggests that the rise of time-dependent behaviour is due to vorticity generation at the inner domain boundary.
7
Kusanovic, Danilo S., Elnaz Seylabi, and Domniki Asimaki. "Optimization of frequency domain impedances for time-domain response analyses of building structures with rigid shallow foundations." Earthquake Spectra 37, no. 3 (January 19, 2021): 1955–79. http://dx.doi.org/10.1177/8755293020981994.
Full textAbstract:
The effects of dynamic soil–structure interaction (SSI) have been extensively studied in the last few decades, and proper analysis for the linear elastic case in frequency domain has been established successfully. However, SSI is rarely considered in the design of building structures, and instead, buildings are frequently analyzed using a rigid base assumption and quasi-static loading conditions that ignore SSI and its dynamic nature. Acknowledging these shortcomings, the National Institute of Standards and Technology (NIST) published in 2012 a set of recommendations on time-domain analyses of SSI for building structures compatible with standard finite element packages for consideration in engineering design. The so-called NIST GCR 12-917-21 report introduced a major simplification to enable frequency domain tools to be implemented in time domain analyses. That is, replacing the frequency-dependent soil impedance functions by a single-valued functions read at the flexible-base structure frequency; This work seeks to quantify the accuracy of this simplification considering fully coupled two-dimensional (2D) finite element models (FEM) as the reference. Using a Bayesian approach based on ensemble Kalman inversion (EnKI) and a range of numerical simulations of soil–foundation–building interaction, we estimate the optimal frequency that can be used to estimate soil impedance for time domain analyses; and we evaluate the improvement that the corresponding impedance offers relative to the full FEM results when compared to time domain analyses performed in accordance to the NIST recommendations outlined above.
8
Ragone, Francesco, and Gualtiero Badin. "A study of surface semi-geostrophic turbulence: freely decaying dynamics." Journal of Fluid Mechanics 792 (March 4, 2016): 740–74. http://dx.doi.org/10.1017/jfm.2016.116.
Full textAbstract:
In this study we give a characterization of semi-geostrophic turbulence by performing freely decaying simulations for the case of constant uniform potential vorticity, a set of equations known as the surface semi-geostrophic approximation. The equations are formulated as conservation laws for potential temperature and potential vorticity, with a nonlinear Monge–Ampère type inversion equation for the streamfunction, expressed in a transformed coordinate system that follows the geostrophic flow. We perform model studies of turbulent surface semi-geostrophic flows in a domain doubly periodic in the horizontal and limited in the vertical by two rigid lids, allowing for variations of potential temperature at one of the boundaries, and we compare the results with those obtained in the corresponding surface quasi-geostrophic case. The results show that, while the surface quasi-geostrophic dynamics is dominated by a symmetric population of cyclones and anticyclones, the surface semi-geostrophic dynamics features a more prominent role of fronts and filaments. The resulting distribution of potential temperature is strongly skewed and peaked at non-zero values at and close to the active boundary, while symmetry is restored in the interior of the domain, where small-scale frontal structures do not penetrate. In surface semi-geostrophic turbulence, energy spectra are less steep than in the surface quasi-geostrophic case, with more energy concentrated at small scales for increasing Rossby number. The energy related to frontal structures, the lateral strain rate and the vertical velocities are largest close to the active boundary. These results show that the semi-geostrophic model could be of interest for studying the lateral mixing of properties in geophysical flows.
9
Mancini, Simone, Koen Boorsma, Marco Caboni, Marion Cormier, Thorsten Lutz, Paolo Schito, and Alberto Zasso. "Characterization of the unsteady aerodynamic response of a floating offshore wind turbine to surge motion." Wind Energy Science 5, no. 4 (December 10, 2020): 1713–30. http://dx.doi.org/10.5194/wes-5-1713-2020.
Full textAbstract:
Abstract. The disruptive potential of floating wind turbines has attracted the interest of both the industry and the scientific community. Lacking a rigid foundation, such machines are subject to large displacements whose impact on aerodynamic performance is not yet fully explored. In this work, the unsteady aerodynamic response to harmonic-surge motion of a scaled version of the DTU 10 MW turbine is investigated in detail. The imposed displacements have been chosen representative of typical platform motion. The results of different numerical models are validated against high-fidelity wind tunnel tests specifically focused on the aerodynamics. Also, a linear analytical model relying on the quasi-steady assumption is presented as a theoretical reference. The unsteady responses are shown to be dominated by the first surge harmonic, and a frequency domain characterization, mostly focused on the thrust oscillation, is conducted involving aerodynamic damping and mass parameters. A very good agreement among the codes, the experiments, and the quasi-steady theory has been found, clarifying some literature doubts. A convenient way to describe the unsteady results in a non-dimensional form is proposed, hopefully serving as a reference for future works.
10
Chen, Zhaohui, Yi Sun, Haiyong Zhang, and Zhaohui Zhang. "A Study on the Fluctuating Pressure Correlation of a Cantilevered Elliptic Annular Roof Structure." International Journal of Structural Stability and Dynamics 16, no. 01 (January 2016): 1640013. http://dx.doi.org/10.1142/s0219455416400137.
Full textAbstract:
A wind tunnel test on a large-span cantilevered elliptical annular roof was carried out. The time series of wind pressures were tested simultaneously on the upper and lower surfaces of a roof structure rigid model, that was exposed to open and suburban boundary layer air flows in various wind directions. The spatial correlation characteristics of fluctuating pressures on the roof structure were analyzed. Both the analyzing results of the correlation coefficient in time domain and the coherence function in frequency domain indicated that the correlation structure of the fluctuating pressure of a large-span roof is sensitive to the location of the investigated taps, the roof geometry, the wind direction, and the inflow turbulence. Therefore, the simulation methodology, using a single coherence function, based on the spatial interval of two taps, ignoring the geometry characteristics and the particular tap locations on the roof, a method commonly used in wind load simulations for high-rise and flat roof structures, is shown to not be appropriate for large-span cantilevered roof structures. This quasi-steady approach cannot be employed to evaluate large-span roof structures.
Conference papers on the topic "Quasi-rigid domains"
1
Cavallaro, Paul V., Michael P. Smith, Jacob D. O’Donnell, Allison Redington, and Eric Warner. "Soft Artificial Muscle Actuators for Undersea Launch and Recovery Systems." In ASME 2022 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/imece2022-93951.
Full textAbstract:
Abstract The pursuit of increased autonomy for undersea and surface vehicles presents challenges for their launch, recovery, positioning and control (LRP&C). Traditional rigid handling and actuator systems are often volume constrained and can limit payloads capacities and operational effectiveness. The need to innovate high capacity and compact actuation technologies is intensified by increasing demands for rapid deployability and stowability, scalability, adaptability, temporary buoyancy and connectivity across the undersea and surface domains. On-demand inflatable and compactable soft actuators may provide unique solutions with robustness needed to operate in extreme underwater environments. This preliminary research investigated the mechanical behaviors, load and stroke capacities, end termination designs and limitations of artificial soft fabric muscles (ASFMs), also known as McKibben muscles, constructed of High Performance Fibers (HPF) for potential launch, recovery, positioning and control of undersea and surface vehicles and interface platforms. Computational mechanics and experimental tests were performed on air-inflated ASFMs constructed of braided fabrics to evaluate their quasi-static behaviors. Both glass and aramid braid materials were studied for a range of diameters and lengths. The computational models supported the fluid/structure interactions by using an Equation of State (EOS) that governed the thermomechanical behaviors of the internal air during volumetric expansion and axial contraction of the ASFMs.
2
Nava, Vincenzo, and Felice Arena. "Effects of Second-Order Extreme Waves on the Dynamics of a Non-Linear Floating Body." In ASME 2012 31st International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/omae2012-84077.
Full textAbstract:
Nowadays technical and scientific communities are increasingly interested in the development of technologies for floating devices which can serve different purposes both in coastal and offshore environment. Thus, strong effort is required in the development of correct and efficient algorithms for studying the behavior of such structures under the action of sea wave loadings. At this purpose, in the past few years several approaches were investigated, both in frequency and in time domains, using linear and non-linear structural models and linear and non-linear wave theories. In this note, the effects of nonlinearities in the wave model on the dynamics of a non-linear floating rigid body model are calculated using the second-order Quasi-Determinism (QD) theory (see [1], [2]; [3]) under the action of extremely high waves. Structural nonlinearities consist essentially in non linear damping and nonlinear stiffness due to mooring lines, following the model shown in Nava & Arena, [4]. Numerical nonlinear simulations were performed by means of an algorithm based on the approach showed in Zheng et al. [5], and the results compared to those provided by the nonlinear QD theory. The purpose of this note is to show not only the effects of nonlinearities in the behavior of a floating body and to compare them with those obtained from a linear approach, but also to estimate them through non linear QD theory under the occurrence of a large wave in order to evaluate the reliability of the proposed approach.
3
Xu, LiMei, Sheng Zeng, NingQun Guo, and Rongming Lin. "Passive Vibration Control of the Head Actuator Assembly in Hard Disk Drive." In ASME 2001 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/detc2001/vib-21572.
Full textAbstract:
Abstract It is known that a quasi-rigid body mode exists in hard disk drives in the frequency range from 3 to 6 kHz and it is caused by the flexibility of the pivot, the mass and structure of the head actuator assembly. The mode hinders performance improvement of servo system in bandwidth. In this paper, a tuned damping device is proposed to suppress this mode. The damping device is to be installed on the arm and hollow space within the voice coil motor on the HDDs. The dynamic characteristics of the head actuator assembly with the tuned damping device are measured in both frequency domain and time domain. It is shown that the tuned damping device can work effectively to suppress the quasi-rigid body vibration of the head actuator assembly and minimize the residual vibration in head positioning.
4
Ormberg, Harald, Elizabeth Passano, and Neil Luxcey. "Global Analysis of a Floating Wind Turbine Using an Aero-Hydro-Elastic Model: Part 1—Code Development and Case Study." In ASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2011. http://dx.doi.org/10.1115/omae2011-50114.
Full textAbstract:
This paper describes the extension of a well proven state-of-the-art simulation tool for coupled floating structures to accommodate offshore wind turbine applications, both floating and fixed. All structural parts, i.e. rotor blades, hub, nacelle, tower, vessel and mooring system, are included in the finite element model of the complete system. The aerodynamic formulation is based on the blade element momentum theory. A control algorithm is used for regulation of blade pitch angle and electrical torque. The system response is calculated by nonlinear time domain analysis. This approach ensures dynamic equilibrium every time step and gives a proper time domain interaction between the blade dynamics, the mooring dynamics and the tower motions. The developed computer code provides a tool for efficient analysis of motions, support forces and power generation potential, as influenced by waves, wind, and current. Some key results from simulations with wind and wave loading are presented in the paper. The results are compared with results obtained with a rigid blade model and quasi-static model of the anchor lines. The modelled wind turbine is the NREL offshore 5-MW baseline wind turbine, specifications of which are publicly available. In the accompanying paper, Global Analysis of a Floating Wind Turbine Using an Aero-Hydro-Elastic Numerical Model. Part 2: Benchmark Study, results from the new analysis tool are benchmarked against results from other analysis tools.
5
Ludvigsen, Arild, Zhi Yuan Pan, Peng Gou, and Torgeir Vada. "Adapting a Linear Potential Theory Solver for the Outer Hull to Account for Fluid Dynamics in Tanks." In ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/omae2013-10284.
Full textAbstract:
The linear boundary value problem for the wave dynamics inside a tank is very similar to the solution for the outer hull. Because of this, the boundary value solver for the outer hull can be re-used for the tank. The oscillating hydrostatic pressure in the tank may also be calculated in the same way as for the outer hull. Thereby, the hydrostatic coefficients from the tank can also be obtained from the outer solution. This makes it, in principle, easy to adapt outer solution computer code to also account for the inner solutions for all the tanks. The procedure is discussed by Newman (2005). We have used it in a different way, isolating the tank solution into more flexible independent sub-runs. This approach provides part-results for the tanks, like added mass and restoring from the tanks. It also has numerical benefits, with the possibility to reuse the calculations for tanks of equal geometrical shape. We have also extended the procedure to account for full tanks without waves and restoring effects. The linear tank fluid dynamics is programmed into a quite general hydrodynamic frequency domain solver, with the possibility of automatic transferring of local loads to structural (FEM) analysis. Results for local loads are presented. A simpler method of quasi-static loading in tanks is discussed, with comparison to the present method. Effects on global motions and local pressure coming from the tank dynamics contributions are pointed out, such as the shifted resonance of the vessel and the added mass which differs from rigid masses of the tanks.
6
Islam, A. B. M. Saiful, Mohammed Jameel, Suhail Ahmad, and Mohd Zamin Jumaat. "Nonlinear Response of Coupled Integrated Spar Platform Under Severe Sea States." In ASME 2012 31st International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/omae2012-83862.
Full textAbstract:
The oil and gas industry has moved towards the offshore deep water regions due to depletion of these resources in shallow and intermediate water depths. Conventional fixed jacket type platforms and bottom supported compliant platforms have been found to be inefficient and uneconomical for exploring these resources in deep water regions. In view of deep water conditions, Spar platforms have been seen to be the most economical and suitable alternative offshore platforms. Several operational Spar platforms such as SB-1, Shell’s ESSCO, Brent Spar, Oryx Neptune Spar, Chevron Genesis Spar and Exxon’s Diana Spar in the Gulf of Mexico and North Sea have shown the effectiveness and success of such platforms in deep-ocean. In deep water conditions, the severity of sea states has substantial effects on the spar platform. The mooring lines contribute significant inertia and damping because of their longer lengths, larger sizes, and heavier weights. Precise motion investigation of platforms should consider these actions in deep waters. However, proper dynamics cannot be assessed by the commonly used decoupled quasi-static method that ignores all or part of the interaction effects between the mooring lines and platform. Coupled analysis, which includes the platform and mooring lines in a single model, is the only way to capture the damping from mooring lines in a consistent manner. In the present study, coupled analysis of integrated Spar-mooring system has been performed. Cylindrical spar hull is treated as a rigid beam element and catenary mooring line as hybrid beam element. Nonlinear dynamic responses have been evaluated under several severe sea states of dissimilar wave heights and wave periods. Damping due to mooring lines has been assessed. An automatic Newmark-β time incremental approach has been implemented to conduct the analysis in time domain. Wave induced spar hull motion in surge, heave and pitch direction along with maximum tension in mooring line has been assessed for different wave conditions with and without current in 1018 m water depth. The time histories of spar responses follow substantial alteration for larger wave heights and wave periods. Maximum tensions in mooring line are very sensitive with momentous value for extreme sea loading. Mooring tension responses are significantly different reflecting the damping effect of mooring lines.
7
Kvittem, Marit I., Petter Andreas Berthelsen, Lene Eliassen, and Maxime Thys. "Calibration of Hydrodynamic Coefficients for a Semi-Submersible 10 MW Wind Turbine." In ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/omae2018-77826.
Full textAbstract:
Hydrodynamic model tests and numerical simulations may be combined in a complementary manner during the design and qualification of new offshore structures. In the EU H2020 project LIFES50+ (lifes50plus.eu), a model test campaign of floating offshore wind turbines using Real-Time Hybrid Model (ReaTHM) testing techniques was carried out at SINTEF Ocean in fall 2017. The present paper focuses on the process of calibrating a numerical model to the experimental results. The concepts tested in the experimental campaign was a 1:36 scale model of the public version of the 10MW OO-Star Wind Floater semi-submersible offshore wind turbine. A time-domain numerical model was developed based on the as-built scale model. The hull was considered as rigid, while bar elements were used to model the mooring system and tower in a coupled finite element approach. First-order frequency-dependent added mass, potential damping, and excitation forces/moments were evaluated across a range of frequencies using a panel method. Distributed viscous forces on the hull and mooring lines were added to the numerical model according to Morison’s equation. Potential difference-frequency excitation forces were also included by applying Newman’s approximation. The quasi static properties of the mooring system were assessed by comparing the restoring force and maximum line tension with the pull-out test. Drag coefficients for the line segments were estimated by imposing the measured fairlead motion from model tests as forced displacement and comparing the calculated and measured dynamic line tension. The linear and viscous damping coefficients were first estimated based on the decay tests, and the tuned damping coefficients were compared to initial guesses based on the Reynolds and Keulegan-Carpenter number at model scale. The results were then applied in the numerical model, and simulations in extreme irregular waves were compared to the experiments. It was found that second order drift forces proved to be significant, particularly for the severe irregular seastate. These could not be modelled correctly applying the potential drift forces together with quadratic damping matrix tuned to the free decay test. And the model with viscous drag coefficients tuned to decay tests also underestimated the slow drift motions. Thus, new viscous drag coefficients were determined to match the low frequency platform response. To inverstigate the performance of the tuned model, comparisons were made for a moderate seastate and for a simulation with both waves and wind on an operating turbine. In the end, possible further improvements to the modelling were suggested.
8
Zhang, Chi, Harrif Santo, Minbo Cai, and Allan Magee. "Dynamic Response of a Generic Self-Elevating Unit in Operation With Hull in Water." In ASME 2022 41st International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/omae2022-78850.
Full textAbstract:
Abstract Self-elevating units (SEUs), with a water-tight hull fitted with long support legs and spudcans, are widely used in offshore drilling and operations, as well as offshore wind turbine installations. SEUs are also known as jack-up rigs. A jack-up rig undergoes several stages of operations involving different leg configurations, such as legs retracted, legs suspended in the water, spudcans pre-loaded into the soil, and legs deployed in the seabed with the hull lifted clear above water. The hull and the legs will therefore be subjected to various external environmental actions. Transit operation (when the hull is in water) is only carried out in mild environmental conditions, due to safety concerns. The dynamic response of the SEU in the transit operation is less investigated in contrast to normal operation when the hull is in elevated condition supported by the legs. In this paper, we investigate the dynamic behavior of a generic (in-house designed) three-legged SEU. The configuration is such that the hull is in the water while the spudcans are secured in the seabed. A nonlinear time-domain model is established for the coupled hull and legs through Cummins’s equation. The hull is assumed as a rigid body with motions in six degrees of freedom, and the hydrodynamic coefficients are calculated from radiation and diffraction analysis. The legs are simplified as lumped mass models with equivalent stiffness value as the prototype, and Morison-type hydrodynamic loads are applied. Various scenarios of boundary conditions are considered, i.e., constant spudcan constraint stiffness, pin, fixed boundary conditions, and incidental cases when up to two spudcans are released while the other is still secured in the seabed. The dynamic responses of the SEU under operating sea conditions are examined. The results are compared to those from the conventional quasi-static analysis where the legs are simplified as linear springs. It is found that the dynamic response of the SEU with the hull-in-water condition can be as large as that in the elevated condition, despite the much milder sea conditions. The operational limit can be significantly reduced if the resonant motion occurs. These results show the importance of a full coupled dynamic analysis for a rational design of an SEU and may serve to guide operations for mobile offshore drilling units. It is even more crucial for certain SEUs where the hulls are intended to be in the water for a longer period, such as offshore wind turbine installation vessels. It may also allow the transit operations to be performed under slightly more severe conditions by better defining safe operational limits and reducing uncertainty.