A numerical simulation analysis method for wave dynamic response and structural performance of a floating oil storage facility
By using CFD methods based on viscous flow theory and the OpenFOAM platform, accurate simulation of floating oil storage facilities under complex wave conditions was achieved. This solved the problems of internal and external water coupling and the influence of multiple factors, improved the calculation accuracy and efficiency, and provided detailed load inputs for structural design.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NANJING UNIV OF SCI & TECH
- Filing Date
- 2026-03-25
- Publication Date
- 2026-07-31
AI Technical Summary
Existing technologies struggle to accurately simulate the dynamic response of floating oil storage facilities under the interaction of strong nonlinear waves and structures. Simulation of the coupling between internal and external water is difficult, and there is a lack of analytical methods that systematically consider the coupling effects of multiple factors such as different sea conditions, internal liquid level height, and wave incident angle.
A CFD method based on viscous flow theory was adopted. Waves were generated through the OpenFOAM platform to establish a floating oil storage facility model. Virtual through-holes were set up to couple internal and external water, separate dynamic pressure and static pressure, and a six-degree-of-freedom motion library was used to solve the coupling motion of fluid and floating body. The influence of multi-factor parameterization was systematically analyzed.
It improves computational accuracy and efficiency, enabling a comprehensive assessment of dynamic response characteristics under complex working conditions, providing precise load inputs, guiding structural design, and reducing computational costs.
Smart Images
Figure CN122491089A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of hydrodynamic calculation and structural analysis technology of marine engineering structures. Specifically, it is a numerical simulation analysis method for wave dynamic response and structural performance of floating oil storage facilities based on CFD. Background Technology
[0002] As offshore oil and gas resource development expands into deeper waters, floating oil storage facilities are gaining increasing attention due to their excellent environmental adaptability and economic advantages. Japan has already built two representative floating oil storage bases, Kamigoto (1988) and Shirashima (1995). Ang et al. from the National University of Singapore proposed a discretely arranged floating hydrocarbon storage and refueling terminal (FHST), which uses a ring-shaped breakwater as the outer structure and houses multiple independent oil storage tank units inside.
[0003] Currently, numerical simulation methods for the dynamic response of floating oil storage facilities are mainly divided into two categories: methods based on potential flow theory and methods based on computational fluid dynamics (CFD). Zhang et al. (Ocean Engineering, 2019) studied the hydrodynamic load and dynamic response of a single floating tank based on potential flow theory. However, this method ignores the fluid viscosity effect, has limitations in simulating strongly nonlinear phenomena such as wave breaking, and is difficult to accurately simulate the coupling effect between internal liquid sloshing and external waves. Huang Tianqi (2016) used the "through-hole method" based on OpenFOAM to realize the coupling simulation of the water inside the tank and the external fluid. However, the research object was a single ship compartment, which did not involve multi-tank systems, nor did it consider the influence of changes in wave incident angle. Miao et al. (Coastal Engineering Journal, 2001) studied the wave resonance phenomenon in the narrow gap between two floating bodies. However, the research object was a simplified two-dimensional rectangular cylinder, which differs greatly from the complex geometry of actual floating oil storage facilities. Shokoohfar et al. (2020) analyzed the dynamic response of prestressed concrete tanks under seismic loads based on ABAQUS, but the study focused on inland tanks and did not consider wave loads.
[0004] In summary, existing technologies suffer from the following main problems: potential flow theory struggles to accurately simulate the interaction between strongly nonlinear waves and structures; simulation of internal and external water coupling is difficult; there is a lack of analytical methods that systematically consider the coupling effects of multiple factors such as different sea conditions, internal liquid level height, and wave incidence angle; and the fluid-structure interaction analysis chain is incomplete. This invention proposes solutions to these problems. Summary of the Invention
[0005] The purpose of this invention is to provide a numerical simulation analysis method for the wave dynamic response and structural performance of floating oil storage facilities.
[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a numerical simulation analysis method for the wave dynamic response and structural performance of floating oil storage facilities, comprising the following steps:
[0007] S1. A numerical wave pool was established based on OpenFOAM, and waves were generated using Stokes theory. A pier model of a floating bridge was built in the wave pool, and numerical simulation was performed under the set wave parameters. The total pressure at preset monitoring points on the surface of the pier columns was decomposed into dynamic pressure and static pressure using Bernoulli's equation. A geometric model of a floating oil storage facility was established in the wave pool. The oil storage tank consists of a central cylinder and multiple floats, and a breakwater structure was also built. Virtual through holes were set on the tank wall using the "through-hole method" to connect the external fluid domain with the liquid inside the tank through air. Pressure detection points were set at specific locations on the oil storage tank.
[0008] S2. Under the marine environment, wave parameters corresponding to different return periods are selected as input conditions for oil storage facilities; multiple typical proportions are selected for the internal liquid level height within the range of 0% to 100% of the total height of the oil storage tank, and multiple typical angles are selected for the wave incident direction within the range of 0° to 90°; the working conditions of a single oil storage tank without a breakwater and a multi-tank system with a U-shaped or annular breakwater are set up respectively; for the floating bridge pier structure, multiple sets of marine wave parameters with different characteristics are also selected as input conditions.
[0009] S3. Based on the oil storage facility model established in step S2 and the calculation conditions set in step S3, the interFoam solver in OpenFOAM is used, combined with the six-degree-of-freedom motion library sixDoFRigidBodyMotion to achieve coupled solution of fluid motion and floating body motion, obtain the motion response time history data of the floating body under wave action, extract the pressure time history data of each monitoring point, and divide the total pressure into dynamic pressure and static pressure through Bernoulli's equation. The pressure results are represented by the circumferential angle and vertical height along the structure, respectively.
[0010] Compared with the prior art, the present invention has the following significant advantages: (1) The present invention adopts the CFD method based on viscous flow theory, which can fully consider key physical processes such as fluid viscosity, flow separation and energy dissipation, accurately reproduce complex flow structures, and has good simulation capabilities for strong nonlinear phenomena such as wave breaking and deck waves. It is more accurate than the traditional potential flow theory method. (2) The present invention cleverly transforms the multi-domain problem of internal and external water coupling into a single numerical domain solution, avoiding complex boundary condition settings, greatly improving computational efficiency and stability, and solving the problem of difficult simulation of internal and external water coupling in the prior art. (3) The present invention systematically establishes a multi-factor parametric analysis system covering different sea state conditions (5-100-year return period), internal liquid level height (0%-100%) and wave incident angle (0°-90°), which can comprehensively evaluate the dynamic response characteristics of floating oil storage facilities under various complex working conditions, and overcome the limitations of existing research that only analyzes a single factor. The system can accurately identify the non-monotonic control effect of the internal liquid level height on the tank movement and the decisive influence of the wave incident angle on the response mode, providing a more comprehensive reference for engineering design. (4) The present invention establishes a dynamic pressure and static pressure separation analysis method, which can accurately obtain the pressure distribution characteristics of different positions (wave-facing surface, back-wave surface, side surface) on the surface of the oil tank, and quantitatively identify the pressure peak and variation law under various working conditions. This method can provide accurate load input for the structural design of the oil tank, effectively guide the local reinforcement and fatigue resistance design of key parts, and overcome the limitation of traditional methods that can only provide the total load. (5) The method of the present invention is simple and easy to implement, based on the open source software OpenFOAM, with low computational cost, and can be widely applied to the dynamic response analysis of various floating marine structures, providing technical support for marine engineering design and safety assessment. Attached Figure Description
[0011] Figure 1 It is a wave numerical pool diagram. Figure 2 The following are wave verification results: (a) shows the wave surface elevation of the theoretical solution and numerical simulation at x = 9 m, and (b) shows the comparison between the instantaneous wave surface shape and the theoretical wave surface shape at t = 15 s.
[0012] Figure 3 (a) is a model diagram of a floating oil storage tank, and (b) is a plan view of the floating oil storage tank. Figure 4 These are the plan view of the oil storage tank and the experimental layout diagram. (a) is the mooring fender system in the experimental test, and (b) is the oil storage tank equivalent to a spring damping module.
[0013] Figure 5 The vector diagram shows the velocity of the oil storage tank at the crest of the wave when the period is 7s. (a) is a three-dimensional overall view, (b) is a two-dimensional enlarged view, and (c) is a two-dimensional overall view.
[0014] Figure 6 These are time-domain results of full-scale oil storage tanks under different cycles. (a) is the result of the sway simulation, (b) is the result of the pitch simulation, and (c) is the result of the heave simulation.
[0015] Figure 7 These are time-domain results of the scaled-down oil storage tank motion under different periods. (a) is the result of the sway simulation, (b) is the result of the pitch simulation, and (c) is the result of the heave simulation.
[0016] Figure 8 The figures show the comparison of numerical simulation results of oil storage tanks under no-load conditions. (a) is the result of the sway simulation, (b) is the result of the pitch simulation, and (c) is the result of the heave simulation.
[0017] Figure 9 The vector diagrams are of the oil storage tank at the crest of the wave when the period is 10 s. (a) is a three-dimensional overall view, (b) is a two-dimensional enlarged view of a local area, and (c) is a two-dimensional overall view. Figure 10 The diagram shows the frequency domain comparison of oil storage tanks under 20% liquid conditions. (a) is the result of the sway simulation, (b) is the result of the pitch simulation, and (c) is the result of the heave simulation.
[0018] Figure 11 These are pressure verification cloud diagrams. (a) is static pressure, and (b) is dynamic pressure.
[0019] Figure 12 These are comparison diagrams of pressure verification at the crest of the wave. (a) is the front side of the wave, and (b) is the back side of the wave.
[0020] Figure 13 These are comparison diagrams of pressure verification during the trough period. (a) is the front side of the wave, and (b) is the back side of the wave.
[0021] Figure 14 The diagram shows the key locations of the oil storage tank. (a) is a cross-sectional view, (b) is a circumferential angle view, (a) is static pressure, (b) is dynamic pressure, and (c) is dynamic / static pressure before the wave crest.
[0022] Figure 15 The diagram shows a comparison of radial pressure before and after the wave crest. (a) is static pressure, (b) is dynamic pressure, and (c) is dynamic / static pressure before the wave crest.
[0023] Figure 16 The diagram shows the circumferential pressure of an oil storage tank without a breakwater at different times under sea state 1. (a) is the circumferential static pressure, and (b) is the circumferential dynamic pressure.
[0024] Figure 17 The following is a time-domain diagram of the pressure of an oil storage tank without a breakwater at a height of z = -2 m in sea state 1. (a) is static pressure and (b) is dynamic pressure.
[0025] Figure 18This is a comparison chart of the pressure values of an oil storage tank without a breakwater at a wave front height of -2 m in sea state 1. (a) is static pressure, and (b) is dynamic pressure.
[0026] Figure 19 This is a radial pressure diagram of an oil storage tank without a breakwater on the wave crest and trough facing the wave. (a) is the static pressure on the wave-facing surface, and (b) is the dynamic pressure on the wave-facing surface. Figure 20 This is a radial pressure diagram of the back wave surface of an oil storage tank with an inner liquid level of 20% without a breakwater, at the crest and trough of the wave. (a) is the static pressure on the back wave surface, and (b) is the dynamic pressure on the back wave surface.
[0027] Figure 21 This is a radial pressure diagram of the inner liquid level 20% oil storage tank without breakwater at the crest and trough of the wave. (a) is the static pressure on the side, and (b) is the dynamic pressure on the side.
[0028] Figure 22 This is a diagram of the circumferential pressure at the crest of a 20% inner liquid level oil storage tank without a breakwater. (a) is the circumferential static pressure, and (b) is the circumferential dynamic pressure.
[0029] Figure 23 This is a diagram of the circumferential pressure at the trough of an oil storage tank with an inner liquid level of 20% without a breakwater. (a) is the circumferential static pressure, and (b) is the circumferential dynamic pressure.
[0030] Figure 24 This is a diagram showing the radial pressure at the crest of the outer liquid surface of an oil storage tank with an inner liquid level of 20% without a breakwater. (a) is the static pressure, and (b) is the dynamic pressure.
[0031] Figure 25 This is a diagram showing the radial pressure at the crest of the liquid surface in an oil storage tank with an inner liquid level of 20% without a breakwater. (a) is the static pressure, and (b) is the dynamic pressure.
[0032] Figure 26 The diagram shows the circumferential pressure at the crest of an oil storage tank without a breakwater at different internal liquid levels. (a) is the static pressure, and (b) is the dynamic pressure.
[0033] Figure 27 This is a diagram of the circumferential pressure at the trough of an oil storage tank without a breakwater at different internal liquid levels. (a) is the static pressure, and (b) is the dynamic pressure.
[0034] Figure 28 This is a radial pressure diagram of an oil storage tank without a breakwater at a wave angle of 45°. (a) is the wave crest dynamic pressure, and (b) is the wave trough dynamic pressure.
[0035] Figure 29 This is a circumferential dynamic pressure diagram of the crests and troughs of an oil storage tank without a breakwater under different wave angles.
[0036] Figure 30 These are the finite element diagram and the plan view of the breakwater. (a) is the surface mesh of the barge, and (b) is the plan view of the barge.
[0037] Figure 31 This is a diagram showing the relative positions of the breakwater and the oil storage tank.
[0038] Figure 32 The vector diagram shows the velocity of an oil storage tank with a breakwater at sea state 1 just before the wave crest. (a) is a three-dimensional overall view, (b) is a two-dimensional enlarged view, and (c) is a two-dimensional overall view.
[0039] Figure 33 The vector diagram shows the velocity of an oil storage tank with a breakwater. (a) represents static pressure, and (b) represents dynamic pressure.
[0040] Figure 34 This is a radial pressure diagram of the crests and troughs. (a) is static pressure, and (b) is dynamic pressure.
[0041] Figure 35 The image shows a comparison of the inner and outer corrugated surfaces of an oil storage tank with a barge. (a) shows the corrugated surface detection location, and (b) shows the corrugated surface value.
[0042] Figure 36 The diagram shows the time-domain pressure results of the oil storage tank with barge at a height of z=-2m under sea state 1. (a) is the static pressure and (b) is the dynamic pressure.
[0043] Figure 37 The image shows the wave propagation position contour map at z = -2 m under different conditions, where (a) is the dynamic pressure value of zero, (b) is the maximum dynamic pressure value, and (c) is the minimum dynamic pressure value.
[0044] Figure 38 This is a comparison chart of different pressure values for an oil storage tank with a barge under sea state 1. (a) is static pressure, and (b) is dynamic pressure.
[0045] Figure 39 The diagram shows the influence of barge on the motion characteristics of oil storage tanks under different sea conditions. (a) is the result of the sway simulation, (b) is the result of the pitch simulation, and (c) is the result of the heave simulation.
[0046] Figure 40 The diagram shows the effect of barge on the pressure characteristics of the oil storage tank under sea state 1. (a) is static pressure and (b) is dynamic pressure.
[0047] Figure 41 The figures show the influence of barge on the motion characteristics of the oil storage tank under different internal liquid level heights. (a) is the result of the sway simulation, (b) is the result of the pitch simulation, and (c) is the result of the heave simulation.
[0048] Figure 42 The diagram shows the effect of barge on the pressure characteristics of the oil storage tank at 80% internal liquid level. (a) is the static pressure at the crest, and (b) is the dynamic pressure at the crest.
[0049] Figure 43 The diagram shows the effect of barge on the motion characteristics of the oil storage tank under different wave angles. (a) is the result of the sway simulation, (b) is the result of the pitch simulation, and (c) is the result of the heave simulation.
[0050] Figure 44 The diagram shows the effect of barge on the pressure characteristics of the oil storage tank under a 45° wave angle. (a) is static pressure, and (b) is dynamic pressure.
[0051] Figure 45 It is a schematic diagram of the invention. Detailed Implementation
[0052] The numerical simulation analysis method for the wave dynamic response and structural performance of floating oil storage facilities of this invention employs a separation of dynamic and static pressure, presenting the pressure distribution law of the structural surface through radial and circumferential pressure. The accuracy of the pressure simulation is verified by comparison with experimental results. Based on this, considering the coupled effects of multiple factors such as the annular breakwater, different sea state conditions (5-100 year return period), internal liquid level height (0%-100%), and wave incident angle (0°-90°), the method systematically analyzes the influence of each factor on the motion response and pressure distribution of the oil storage tank, revealing the shielding effect of the breakwater, the non-monotonic control effect of the internal liquid level height on the tank motion, and the decisive influence of the wave incident angle on the response mode.
[0053] The present invention will be further described below with reference to the accompanying drawings and embodiments.
[0054] The numerical simulation analysis method for wave dynamic response and structural performance of floating oil storage facilities of the present invention includes the following steps:
[0055] Step 1: Establish a numerical wave pool based on the OpenFOAM open-source software platform, generate waves using Stokes' first-order wave theory, and verify the correctness of the results using specific wave environments and boundary conditions.
[0056] Step 2: Create models of the pontoon bridge piers, floating oil storage facilities, and external breakwaters, and import them into OpenFOAM. Set the inherent properties of the objects, detect the motion results, and compare them with experimental results.
[0057] Step 3: In the context of a marine environment, wave parameters corresponding to different return periods are selected as input conditions for oil storage facilities, covering waves from common to extreme waves, and the stress characteristics of the structure are analyzed.
[0058] Step 4: In a marine environment, select several typical proportions within the range of 0% to 100% of the total height of the oil storage facility, covering the period from no load to full load, and analyze the stress characteristics of the structure.
[0059] Step 5: In the context of a marine environment, select multiple typical angles and proportions within the range of 0° to 90° for the wave incident direction of the oil storage facility, and analyze the stress characteristics of the structure.
[0060] Step 6: Perform numerical simulation calculations on the oil storage tank with annular breakwater based on the wave environment described in Steps 3-5, and compare the results.
[0061] Example 1: Establishment and Verification of a Numerical Wave Pool
[0062] This embodiment first establishes a numerical wave pool. The computational domain dimensions are 20.5m × 1.0m × 0.8m, with a water depth of 1.7m, as shown in Figure 1. A structured mesh is used for mesh generation, with the number of meshes refined in the wave height direction to 1 / 20 of the wave height and in the wavelength direction to 1 / 100 of the wavelength. The wave conditions used are a Stokes first-order wave with a period T = 1.73s and a wave height H = 0.071m. The computational domain dimensions are set according to the following conditions: the distance from the inlet of the wave-generating zone to the float is greater than 3 times the wavelength; the distance from the outlet of the wave-dissipating zone to the float is greater than 2 times the wavelength; and the distance from the left and right boundaries to the center of the float is greater than 1.5 times the wavelength. The mesh generation adopts a refinement standard of 1 / 20 of the wave height in the wave height direction and 1 / 100 of the wavelength in the wavelength direction. The aspect ratio of each mesh does not exceed 1:4, and the height of the free surface densification zone is set to 1.5 times the wave height.
[0063] Wave generation employs the boundary wave generation method, specifying velocity and phase volume fraction at the inlet boundary according to wave theory. Wave dissipation utilizes a numerical damping region, adding a damping term in the outlet region to gradually dissipate wave energy. A comparison of the Stokes first-order wave theory solution and the numerical simulation results, as shown in Figure 2, reveals a waveform error of no more than 2%. In the long-term simulation of 45–80 s, as shown in Figure 3, the wavefront elevation maintains a stable periodicity, with a wave height attenuation rate of approximately 0.8% per period, indicating that the numerical model possesses good energy conservation characteristics.
[0064] Example 2: Validation of Oil Storage Tank Model and Dynamic Pressure Verification
[0065] This embodiment validates the oil storage tank model. STL format files for the floating bridge piers, floating oil storage facilities, and external breakwater are created and imported into OpenFOAM. The models are then embedded into the fluid computational domain using the snappyHexMesh command, completing mesh generation and model integration. The mass, moment of inertia, mooring chain stiffness, and water tank damping coefficient are set in the dynamicDict file. The scaled-down model of the oil storage tank is 0.634m long, 0.634m wide, and 0.275m high, with an inner diameter of 0.509m, an outer diameter of 0.529m, an external float diameter of 0.152m, a bottom plate thickness of 0.015m, and a float mass of 34.19kg. Its shape consists of a central cylinder and multiple floats. The floats provide additional buoyancy to maintain the tank's stability in waves. A virtual through-hole method is used to create virtual through-holes in the tank wall, connecting the external fluid domain with the internal liquid through air, thereby simulating pressure transmission and free surface fluctuations between the internal and external water bodies. Pressure detection points were arranged along the height direction on the wave-facing, wave-back, and side surfaces of the oil storage tank, as shown in Figures 3 and 4. The interFoam solver was used in conjunction with the six-DOF motion library sixDoFRigidBodyMotion to achieve coupled solution of fluid motion and floating body motion, obtaining the time history data of the floating body's six-DOF motion response under wave action, including displacement and angular changes in the sway, pitch, and heave directions. The regular wave period range of the time history curves is from 4s to 12s. The 3D vector diagram of the scaled model is shown below. Figure 5 As shown, the scaled-down time-domain results are as follows: Figure 6 As shown, the scaled frequency domain results are as follows: Figure 7 As shown in the figure, under no-load conditions, as the wave period of the scaled-down oil storage tank increases from 4s to 8s, the motion responses in all three degrees of freedom—sway, pitch, and heave—gradually increase. The heave response is the strongest, exhibiting a significant resonance peak at approximately 8s, corresponding to the tank's natural heave period. The pitch response continues to increase with the period, peaking at 8s. The RAO value in the sway direction increases with the period, reaching a peak at approximately 11s and then decreasing. The frequency domain results of the full-scale model are shown in the figure. Figure 8 As shown, the vector image is as follows Figure 9 As shown.
[0066] The frequency domain results of the oil storage tank's motion response under the condition of 20% internal liquid level are as follows: Figure 10 As shown, the oil storage tank values and experimental values generally agree well in terms of trend and numerical values. The RAO value in the sway direction is close to the experimental value throughout the entire period, especially in the 6-9s range where the consistency is relatively high; the numerical simulation results in the pitch direction are relatively consistent with the experimental data; the heave direction is slightly lower than the experimental value in the medium period range, but basically consistent with the experimental value in the short and long period regions.
[0067] Dynamic pressure verification: Based on the experimental results of bridge pier piles by Xu and Corvaro, dynamic pressure verification was conducted. Monitoring points were pre-set on the surface of the bridge pier pile to capture the pressure changes on the structural surface under wave action. The numerical model used a Stokes first-order wave with a wavelength of 3m, wave height of 0.1m, period of 1.733s, water depth of 0.35m, and pile diameter of 0.1m. The total pressure was divided into dynamic and static pressure using Bernoulli's equation. The pressure distribution around the cylinder was compared and analyzed. The final calculated pressure contour map is shown below. Figure 11 As shown, the pressure contrast between the peaks and troughs is as follows: Figure 12 , Figure 13 As shown, dynamic pressure is positive at the crest and negative at the trough, with the directional change reflecting the dynamic pressure variation under wave action; static pressure remains relatively stable at different wave phase angles. The dynamic pressure variation trend obtained from OpenFOAM simulation is consistent with the experimental results, verifying the accuracy of the numerical model in dynamic pressure simulation. The simulated dynamic pressure value on the wave-facing side is slightly larger than the experimental value, while the simulated dynamic pressure value on the wave-receding side is slightly smaller. The numerical solution for static pressure agrees well with the experimental measurements in both trend and amplitude.
[0068] Example 3: Dynamic Response Analysis of Oil Storage Tanks under Different Sea States
[0069] This embodiment conducts parametric analysis for different sea state conditions and sets key detection points for the oil storage tank, such as... Figure 14 As shown. Set sea state 1 (period 6.98s, wave height 2.57m), sea state 2 (period 7.89s, wave height 3.04m), sea state 3 (period 9.66s, wave height 4.39m), and sea state 4 (period 10.49s, wave height 4.88m).
[0070] The radial pressure results before and at the wave crest under sea state 1 are as follows: Figure 15 As shown, the circumferential pressure results are as follows: Figure 16 As shown in the figure, the pressure variation of the oil storage tank before and at the wave crest in sea state 1 can be observed. The pressure variation curve of the oil storage tank over time is shown in the figure. Figure 17 As shown, the circumferential pressure results are as follows: Figure 18 As shown in the figure, the pressure in the oil storage tank changes over time.
[0071] Based on the vertical pressure distribution along the height direction under different sea states, as follows: Figure 19 , Figure 20 , Figure 21 As shown, the circumferential pressure results along the angle arrangement from small to large are as follows: Figure 22 , Figure 23As shown in the figure, the dynamic pressure on the wave crest, the back wave surface, and the lateral surface all increase first and then decrease with increasing sea state, reaching an extreme value at sea state 2. The maximum lateral dynamic pressure at wave crest is 18.63 kPa, and the minimum lateral dynamic pressure at wave trough is -15.27 kPa. At a height of z = -2 m, the circumferential pressure shows the lowest dynamic and static pressure values at wave crest 1, the highest static and dynamic pressure values at wave crest 4 on the wave-facing side at sea state 4, and the highest static and dynamic pressure values at the lateral and back wave surfaces at sea state 2.
[0072] Example 4: Dynamic Response Analysis of Oil Storage Tanks under Different Internal Liquid Levels
[0073] This embodiment conducts parametric analysis for different internal liquid level heights. Three operating conditions are set with internal liquid level heights of 20%, 40%, and 80%, and the wave condition is set to sea state 2 (period 7.89s, wave height 3.04m).
[0074] The motion response results of the oil storage tank show that the internal liquid level has a non-monotonic controlling effect on the motion amplitude. The response value is largest when the tank is unloaded; the motion amplitude decreases at 20% liquid level, the added mass increases the system inertia, and the liquid sloshing consumes some energy; the response decreases further at 40% liquid level; at 80% liquid level, the natural frequency of the internal liquid sloshing is close to the wave frequency, triggering coupled resonance, and the motion amplitude increases.
[0075] External pressure load on the oil storage tank during peak pressure period, such as Figure 24 As shown, the internal pressure load is as follows Figure 25 As shown; the circumferential pressure at the crests and troughs is as follows Figure 26 , Figure 27 As shown in the figure, the dynamic pressure at the external liquid surface first decreases and then increases or continues to decrease as the liquid level rises, depending on the specific location. The dynamic pressure at the internal liquid surface decreases as the liquid level rises, reaching its maximum absolute value (-21.52 kPa) at 20% liquid level, indicating the most intense internal liquid sloshing. The difference in static pressure at the external liquid surface is related to the change in the height of the internal liquid surface under wave action. When the oil storage tank is empty, the draft is shallow, and the static pressure is low; at 80% liquid level, the draft increases due to the filling of the internal liquid surface, resulting in a higher static pressure value.
[0076] Example 5: Dynamic Response Analysis of Oil Storage Tanks under Different Wave Incident Angles
[0077] This embodiment conducts parametric analysis for different wave incident angles. Three operating conditions are set with wave incident angles of 0°, 45°, and 90°, and the wave condition is set to sea state 2 (period 7.89s, wave height 3.04m).
[0078] Motion response analysis shows that the pitch and heave responses are most significant under the 0° upwind wave condition; the pitch response is largest (17.6 cm) and the heave response is smallest (17.3 cm) under the 45° oblique wave condition; the pitch response is smallest (13.6 cm) under the 90° transverse wave condition, and the heave response is comparable to that under the 0° condition. The wave incidence direction has a decisive influence on the structural response mode.
[0079] The result of vertical pressure is as follows Figure 28 As shown, the results of the circumferential pressure are as follows: Figure 29 As shown: During the wave crest phase, the lateral dynamic pressure is maximum at 0° and minimum at 90°. During the wave trough phase, the lateral dynamic pressure is minimum at 0° and maximum at 45°. The circumferential dynamic pressure curves at 0° and 90° wave angles are roughly symmetrical, while the pressure distribution at 45° wave angle is asymmetrical.
[0080] Example 6: Dynamic Response Analysis of a Multi-Tank System with Breakwater
[0081] This embodiment analyzes a modular multi-tank system with a ring-shaped breakwater. The breakwater (barge) is 130.2m long, 85.32m wide, and 6m high, with a draft of 4m and a mass of 24,938,634kg. Its radii of gyration are 44.35m, 30.85m, and 42.47m. Two oil storage tanks are placed side-by-side in a moonpool, 26.7m apart, with a distance of 4.5m between the tanks and the moonpool wall. A detailed model is shown below. Figure 30 , Figure 31 As shown.
[0082] Motion response analysis shows that, under sea state 1, the maximum displacement of the oil storage tank with breakwater is 6.14 cm in the longitudinal direction and 20.14 cm in the heave direction. The amplitudes of motion in all three directions are significantly lower than those without a breakwater. Figure 32 , Figure 33 , Figure 34 , Figure 35 as well as Figure 36 It is clear that the breakwater effectively suppresses the direct impact of waves on the storage tank through its shielding effect. Figure 37 as well as Figure 38 This displays the pressure cloud map and circumferential pressure results of the oil storage tank's wave-facing surface under different dynamic pressure values.
[0083] Comparison of motion response results of oil storage tanks with and without breakwaters under different sea states. Figure 39 As shown, the results of the pressure comparison along the circumferential direction are as follows: Figure 40As shown, the RAO increases with the wave period, but the increase is less than that in the case without a breakwater. The heave direction increases from 6.14 cm in sea state 1 to 22.88 cm in sea state 4; the heave direction increases from 20.14 cm to 76.34 cm; and the pitch direction increases from 0.04 degrees to 0.19 degrees. Frequency domain analysis shows that the RAO in all three directions exhibits an upward trend, and no significant resonance peaks were observed within the analysis period, reflecting the tuning effect of the breakwater.
[0084] The motion response of the tank with breakwater at different internal liquid levels differs from that without a breakwater, as shown below. Figure 41 As shown, the circumferential pressure results are as follows: Figure 42 As shown, the response values of the oil storage tank with breakwater in both the sway and pitch directions continuously decrease with the increase of the internal liquid level. This is mainly due to the dominance of mass inertia; the increased total mass of the system makes it more difficult to be propelled by waves. The heave direction exhibits complex characteristics: the response is minimal at 20% liquid level, slightly increases at 40% liquid level, and further increases at 80% liquid level. This phenomenon indicates that although the breakwater effectively suppresses external wave excitation, the internal liquid sloshing still couples with the tank's motion. At high liquid levels, the natural frequency of the sloshing approaches the wave frequency, triggering a resonance effect.
[0085] Different wave direction angles have significantly different effects on multi-tank systems with breakwaters. Figure 43 , Figure 44 The results of the motion response and circumferential pressure of the oil storage tanks are presented. Under the 0° wave-facing condition, the sway, heave, and pitch responses are most prominent, with the waves directly impacting the front of the breakwater, resulting in the highest energy transfer efficiency. Under the 45° oblique wave condition, the lateral motion responses such as sway, roll, and pitch are enhanced, and the motion responses of the two tanks differ, reflecting the asymmetric coupling effect of the multibody system under oblique wave action. Under the 90° transverse wave condition, the roll motion reaches its maximum, but the sway response is the minimum. Compared with the condition without a breakwater, the motion amplitude of the system with a breakwater is significantly reduced at all wave angles, with the heave suppression effect being the most significant, reaching a reduction of 40%-60%.
Claims
1. A numerical simulation analysis method for the wave dynamic response and structural performance of a floating oil storage facility, characterized in that, Includes the following steps: S1. A numerical wave pool was established based on OpenFOAM, and waves were generated using Stokes theory. A pier model of a floating bridge was built in the wave pool, and numerical simulation was performed under the set wave parameters. The total pressure at preset monitoring points on the surface of the pier columns was decomposed into dynamic pressure and static pressure using Bernoulli's equation. A geometric model of a floating oil storage facility was established in the wave pool. The oil storage tank consists of a central cylinder and multiple floats, and a breakwater structure was also built. Virtual through holes were set on the tank wall using the "through-hole method" to connect the external fluid domain with the liquid inside the tank through air, and pressure detection points were set at specific locations on the oil storage tank. S2. Under the marine environment, wave parameters corresponding to different return periods are selected as input conditions for oil storage facilities; multiple typical proportions are selected for the internal liquid level height within the range of 0% to 100% of the total height of the oil storage tank, and multiple typical angles are selected for the wave incident direction within the range of 0° to 90°; the working conditions of a single oil storage tank without a breakwater and a multi-tank system with a U-shaped or annular breakwater are set up respectively; for the floating bridge pier structure, multiple sets of marine wave parameters with different characteristics are also selected as input conditions. S3. Based on the oil storage facility model established in step S1 and the calculation conditions set in step S2, the interFoam solver in OpenFOAM is used, combined with the six-degree-of-freedom motion library sixDoFRigidBodyMotion to achieve coupled solution of fluid motion and floating body motion, obtain the motion response time history data of the floating body under wave action, extract the pressure time history data of each monitoring point, and divide the total pressure into dynamic pressure and static pressure through Bernoulli's equation. The pressure results are represented by the circumferential angle and vertical height along the structure, respectively.
2. The numerical simulation analysis method according to claim 1, characterized in that: The Bernoulli equation mentioned in step S1 is: (1) (2) In the formula, P is the static pressure; As a pressure force; For dynamic pressure; Total pressure; Pre-set monitoring points are arranged along the height and circumference of the bridge pier column surface to capture the pressure distribution on the structural surface under wave action; pressure detection points are arranged along the height of the wave-facing, wave-back, and side surfaces of the oil storage tank; the relative position between the ring breakwater and the oil storage tank is determined according to the actual engineering layout.
3. The numerical simulation analysis method according to claim 1, characterized in that: In step S2, the wave parameters corresponding to different return periods cover the peak period and wave height range from common waves to extreme waves; the internal liquid level height is selected within the range of 0% - 100% of the total height of the tank; and the wave incident direction is selected as 0°-90° as a typical angle.
4. The numerical simulation analysis method according to claim 1, characterized in that: In step S3, the interFoam solver is used in conjunction with the six-DOF motion library sixDoFRigidBodyMotion to achieve coupled solution of the fluid and solid domains through the PIMPLE algorithm. Paraview post-processing is used to extract pressure data by slicing the structure along a specific height z-axis. Radial pressure results are extracted by slicing the structure along the circumferential angle and along the x-axis and y-axis of a certain facade of the floating structure. The two pressure results are arranged in ascending order of angle and ascending order of height, respectively, to analyze the spatial distribution of pressure.