Calm Conditions Research Articles

Seasonal variation in microplankton communities in Suttsu, Hokkaido, northern Japan, from 2020 to 2022

Southwestern Hokkaido faces intricate physiological and chemical changes. Subsequently, changes in lower trophic levels are of concern, but fully understanding the relationship between microplankton and hydrography in this region is required. To examine the relationship between the microplankton community (diatoms, dinoflagellates, ciliates, and euglenoids) and environmental factors in Suttsu, Hokkaido, water samples were collected at 4–15-day intervals from August 2020 to August 2022 at Yokoma Port. Diatoms were dominant in the study area, with an apparent seasonal change in species composition. Lower phytoplankton cell density was observed in the second year than in the first year during autumn and winter because of low temperatures and light intensity in the second year. A significant decrease in the number of attached diatoms (Navicula spp.) was observed during the winter of the second year, possibly due to calm conditions (low tide and wind speed), which prevent the detachment of weakly attached species. Large blooms of euglenoids (Eutreptiella gymnastica and E. marina) in April and May were caused by the exclusive use of nutrients from the inflow of river water during the snowmelt season. Warm-water species sporadically occurred, suggesting their transportation by the Tsushima Warm Current. Temperature, nutrients, and light intensity primarily control microplankton communities, which vary seasonally. These findings led to the prediction of lower trophic levels due to the impact of warm water inflow.

Numerical Investigation on the Motion of a High-Speed Planning Hull in Calm Water Condition using RANSE Method

Planing hulls were commonly used in both civilian and military situations. The prediction of the motion of the planing hull was complicated due to the trim angle and sinkage oscillations caused by the lift variations and complex hydrodynamic interactions at high speeds. To evaluated the motion of the planing hull, it was essential to analyse the hydrodynamic performance of the planing hull at high speed. This paper presented a CFD method for calculating the hydrodynamics of a planing hull in calm water conditions at different Froude numbers. The numerical method was based on the Reynolds-averaged Navier-Stokes equation (RANSE). The volume of fluid (VOF) and two degrees of freedom equations were utilized. An efficient procedure was introduced to solve numerical divergence in numerical simulations. Resistances of the planing hull in numerical results were compared with experimental results to verified and validated the used RANSE method.

Numerical Simulation Flow Around The 4600DWT Cargo Ship in Calm Water Condition Using RANSE Method

Information about the flow field around the ship may enable the designers to improve ship hull form concerning ship hydrodynamics. The flow around the ship can be obtained through model tests in towing tank and simulations. However, the experimental method provides the most reliable data about flow around the ship, but this method is too expensive and time-consuming. Currently, the RANSE (Reynolds – averaged Navier – Stokes equation) method has been widely employed in predicting the ship resistance and flow around the ship in the ship design process due to it provides relatively accurate results, savings in time and money compared to the experimental method. Therefore, this paper deals with the numerical results of the study flow around the 4600DWT cargo ship, which operate on Vietnam’s river-sea routes in calm water condition at different ship speeds using the RANSE method. The effect of ship speed on ship resistance components, wave pattern, wave profile along the ship, distribution of dynamic pressure, and wall shear stress on the ship’s hull surface and nominal wake field are presented and analysed in the paper.

Experimental study on outdoor sound propagation under various meteorological conditions

From the winter of 2018 through the spring of 2021, outdoor sound propagation experiments were repeatedly conducted three times a day on weekdays at a glider airfield in Hokkaido, Japan. In each experiment, impulse responses at the points of 155 m and 300 m from sound sources were measured. The ground surface condition of the experimental field was grass-covered in summer and snow-covered in winter. The monthly averages of sound pressure levels under upwind, downwind, and calm conditions were calculated every month. The data show that the seasonal variation depends on wind conditions, propagation distance, and frequencies. At the point of 300 m from sound sources, the seasonal variations are small under downwind conditions, whereas the range of variations is about 10 dB at high frequencies under upwind conditions and calm conditions. The relationship between vector wind speed and excess attenuation is discussed focusing on differences in atmospheric stability, snowfall, and snow cover conditions, respectively. We also introduce trial calculation results assuming the logarithmic-liner effective sound speed profiles and the parameters of turbulence proposed in previous studies.

Ecological and sediment dynamics response to typhoons passing from the east and west sides of the Changjiang (Yangtze River) Estuary and its adjacent sea area

The hydrodynamic environment of the Changjiang (Yangtze River) Estuary and its adjacent sea area frequently experiences the influence of typhoon activities during the summer season. However, the differences in responses to typhoons with different trajectories are still poorly understood. Using buoy observations with synchronous satellite images, we investigated the sediment dynamics response to Typhoon Danas and Lekima, which passed through the Changjiang Estuary and its adjacent sea area from the east and west sides, respectively. The results indicated that wind forcings disrupted the semidiurnal cycles of ocean currents, leading to southeastward or northwestward residual currents during typhoons Danas and Lekima, respectively. The residual current velocity was typically below 150 mm/s under calm conditions but exceeded 200 mm/s, reaching up to 600 mm/s during typhoon conditions. Typhoon Danas (Lekima) generated onshore (offshore) Ekman transport in the surface layer, resulting in coastal downwelling (upwelling) and bottom offshore (onshore) currents due to the Ekman pumping (suction) effect. Typhoon Danas shifted the Changjiang Diluted Water from northeastward to southeastward, triggering the post-typhoon phytoplankton bloom, while Typhoon Lekima strengthened and even drove the detachment of the Changjiang Diluted Water. These findings suggest the need for different preventive strategies based on the trajectory of each typhoon, considering the potential land damage caused by west-side typhoons and the occurrence of post-typhoon Harmful Algal Blooms resulting from east-side typhoons. Additionally, sediment transport primarily occurred in the bottom layer, governed by the combined effect of tidal currents and typhoon-driven bottom currents. Typhoon Danas, located on the east side of the Changjiang Estuary, led to offshore (positive cross-shore) sediment flux and southwestward (negative along-shore) sediment flux. Conversely, Typhoon Lekima, situated on the west side, caused onshore (negative cross-shore) sediment flux and northeastward (positive along-shore) sediment flux. These findings suggest that existing sediment records may underestimate the frequency and intensity of historical typhoon activities.

ANALISIS KEPUASAN PENGUNJUNG DAN POTENSI PENGEMBANGAN PADA OBJEK WISATA PANTAI MUTUN DI KABUPATEN PESAWARAN

This study aims to analyze the level of visitors’ satisfaction at Mutun Beach, the tourist attributes that need to be improved and maintained by Mutun Beach, and to find out the driving and inhibiting factors development of Mutun Beach. The method used in this research was a survey method. The samples in this study were 4 Mutun employees and 77 visitors, which were taken using purposive sampling and accidental sampling methods. Data collection was carried out in January - February 2023. The data analysis methods used were Customer Satisfaction Index (CSI), Importance Performance Analysis (IPA), and descriptive analysis. The results of this study indicated that the level of visitor satisfaction is in the "Satisfied" category with a CSI value of 74.77%. Based on the IPA method, tourism attributes that need to be improved are the condition of game facilities such as banana boats, rubber boats and water booms, the safety of water boom, and the condition of toilet and prayer room facilities. Tourism attributes that need to be maintained are the attractiveness of the beach, cleanliness, comfortable atmosphere, calm sea water, various and condition of infrastructure and game facilities, and good service. Factors that are driving the development of Mutun Beach are high tourist attractiveness, easy accessibility, complete facilities, good service and management, and government’s role. The inhibiting factors are limited promotion, competitors or other beaches around Mutun, and limited funds and human resources.Key words: CSI, development potential, IPA, visitor satisfaction

Cool season near-surface wind speed trends across the central Appalachian Mountains region of the eastern United States, 1995-2022

ABSTRACT Prompted by recent findings of a common trend toward lesser near-surface winds (NSW), or stilling, time series of cool season NSW variables for 20 stations in the central Appalachian Mountains of the eastern United States were examined for trends during the period 1995–2022. While not universal across the station array, results generally indicate an increase in the frequency of calm conditions, a decrease in mean wind velocity, and a decrease in the frequency of high-wind days. Contrasting this was a general increase in high-wind gust days. The evidence for stilling was supported by an increase in the frequency of days with a 12-hour pressure change of zero and an apparent strengthening and northwestward expansion of the subtropical ridge over the region. Supporting the increase in high-wind gust days was an increase in the frequency of days with a large 3-hour pressure change, and lesser geopotential heights in the lower atmosphere northwest of the region, which contrasts the expanding subtropical ridge and together presents the potential for periodic placement of stronger dynamics across the region.

Grasping extreme aerodynamics on a low-dimensional manifold

Modern air vehicles perform a wide range of operations, including transportation, defense, surveillance, and rescue. These aircraft can fly in calm conditions but avoid operations in gusty environments, encountered in urban canyons, over mountainous terrains, and in ship wakes. With extreme weather becoming ever more frequent due to global warming, it is anticipated that aircraft, especially those that are smaller in size, will encounter sizeable atmospheric disturbances and still be expected to achieve stable flight. However, there exists virtually no theoretical fluid-dynamic foundation to describe the influence of extreme vortical gusts on wings. To compound this difficulty, there is a large parameter space for gust-wing interactions. While such interactions are seemingly complex and different for each combination of gust parameters, we show that the fundamental physics behind extreme aerodynamics is far simpler and lower-rank than traditionally expected. We reveal that the nonlinear vortical flow field over time and parameter space can be compressed to only three variables with a lift-augmented autoencoder while holding the essence of the original high-dimensional physics. Extreme aerodynamic flows can be compressed through machine learning into a low-dimensional manifold, which can enable real-time sparse reconstruction, dynamical modeling, and control of extremely unsteady gusty flows. The present findings offer support for the stable flight of next-generation small air vehicles in atmosphere conditions traditionally considered unflyable.

Simulation of encounter rates between zooplankton organisms and microplastics in a tropical estuary.

Coastal estuarine systems may hold a large number of microplastic particles, which predators often mistake for prey. This study estimated the encounter rates between microplastics (alleged prey) and zooplankton having different feeding modes, trophic positions, swimming velocities, and perception distances, under calm and turbulent conditions, and during two seasons. Surface water samples were taken at 10/12 sites of the Sontecomapan lagoon, southern Gulf of Mexico, to quantify microplastic concentration. Zooplankton organisms considered were copepods, chaetognaths, and luciferids, common organisms in the lagoon. In June, at surface waters and during calm conditions, mean encounter rates were 1.5, 2450, and 980 particles per individual per hour, that is, for copepods, chaetognaths, and luciferids, respectively. When the wind blows (0.8 m s-1) encounter rates were 1.2, 1.4, and 2.6 times higher than in calm conditions. In October, mean encounter rates under calm conditions were 0.2, 355, and 142 particles per individual per hour, for copepods, chaetognaths, and luciferids; these values increase 1.3, 1.6, and 3.3 times when the wind blows (1.12 m s-1). The major number of encounters in June was due to a higher concentration of microplastics, despite the lower turbulent velocity. Regarding their trophic position, we propose that secondary consumers (chaetognaths and luciferids) are more affected because they could eat microplastics via contaminated prey or accidentally ingest them owing to confusion in the motion signals, especially under turbulent conditions. Another consequence of encounters could be the entanglement of microplastics in the body of the animals, especially in those with complex morphology, such as crustaceans. Encounters between zooplankton and microplastics do not always result in ingestion or entanglement, but the encounters are the first step in the case of occurrence.

Thank you very much, Professor Seung Taeg Oh! (The jewel makes our life to be strong and to be firm, and the jewel gives us the beauty of our lives!) (Tcheonzamun 033rd-048th)

French missionary Dallet (1874) wrote in his book that Korean people does not have same culture with Chinese people, for example the language, the history, the race etc. And Dallet (1874) also wrote that both old Chinese people and old Korean people used ‘The thousand character essay’ as the textbook for teaching their children for Chinese character. The thousand character essay is called as Tcheonzamun in Korea. The word of Tcheonzamun means ‘The thousand character essay’. Park et al., (2021a, 2021b) studied the translation of Tcheonzamun. And the present researcher will try to translate this ‘The thousand character essay’ poem (Tcheonzamun 033rd-048th). The present researcher tried to translate the poem from ‘The thousand character essay’, in other word, from ‘Tcheonzamun’. A Tcheonzamun poem has 16 Chinese letters. There are two methods for this translation of Tcheonzamun. The first method is through the meaning of Chinese character, and the second one is through Korean pronunciation of Chinese character. On the present study, the Tcheonzamun poem (Tcheonzamun 033rd-048th) was translated through the meaning of Chinese character. The title of this work is ‘Thank you very much, Professor Seung Taeg Oh! (The jewel makes our life to be strong and to be firm, and the jewel gives us the beauty of our lives!)’. This is the translation of the poem from ‘the thousand character essay’ (Tcheonzamun 033rd-048th). <Number in Tcheonzamun Chinese characters (the pronunciation on Korean language and written in English alphabet)> 033-036 雲(Un) 騰(Deung) 致(Tchi) 雨(U). “I hope that this thing will be done in a short time (致). And I hope that several other things also will be done completely at the same time!” For example, I wish that the cloud (雲) come to the high heaven (騰) directly. And then, I hope that the rain (雨) might fall. It is a great thing. 037-040 露(No) 結(Gyeol) 爲(Wi) 霜(Sang). To do great thing? But in the real sense, to do great thing is possible? To do great thing is not easy. It is difficult. In order for ‘a great work’ to become realized, what is necessary? The great effort is not always necessary. For example, do you want to obtain (爲) some of frost (霜)? In this case, only the dew (露) is necessary in order to make (結) the frost. What does it mean? If you prepare the small thing, here the dew. And then, the great thing, here the frost, will be obtained. 041-044 金(Geum) 生(Saeng) 麗(Ryeo) 水(Su). Do you want that the beauty on the calm and simple condition (麗) comes out (水) from the person or from the thing? In order for such a thing to be done for the person or for the thing, at first, the strong property (金) must exist (生) in the human-being or in the material. For example, the beautiful frost can be obtained only when the dew itself becomes firm. 045-048 玉(Ok) 出(Tchul) 崑(Gon) 岡(Gang). And how does such a firmness result in? In order for these small parts of the frost to stand greatly (岡) like the high mountain (崑), the small parts of the frost must give the bright or the luminous light (出) like the jewel (玉). In order for the small parts of the dew to become the frost, the property of the firm and of the strong is necessary. And then, where does it come the strong property of the frost? The luminous light is necessary. The jewel shaped of round bead or marble is necessary. This Tcheonzamun poem tells us next thing. The appearance is not important, but the mind inside is important. The master who has created the Tcheonzamun poem says to us as follow. “The jewel makes our life to be strong and to be firm, and the jewel gives us the beauty of our lives!”

Wave Forcing Assessment at Regional Scale in a Climate Change Scenario: The Sardinia Case Study

In recent decades, the world’s population is progressively shifting towards coastal areas, and it is estimated that it could reach 1 billion by 2050. On the other hand, meteocean forcings show increasing modification in terms of the occurrence and frequency of energetic events related to climate change trends. Then, the definition of adaptation strategies is crucial to managing coastal areas, especially in the most densely populated or highly valued tourist and environmental areas. Meaningful long-term strategies should then be based on quantitative estimation of future scenarios in a changing climate. Although most of the studies in the literature focus on extreme events, this paper aims to assess, through synthetic indicators, whether and how average and mild energy conditions related to wave climate will vary considering the current situation compared to future projections. The study is based on the analysis of wave data. The projection of average and mild energy conditions can indeed influence, just for example, the long-term morphodynamics of sandy beaches and the quality of bathing waters. Data extracted from the Copernicus database are considered. The methodology has been applied to the case of Sardinia island at a regional scale. Then, the aim of this paper is twofold: on the one hand, a method is proposed to evaluate the variation of average and mild wave conditions; on the other hand, it aims to apply the method to the case study of the Sardinia coastal area to highlight its feasibility. Results confirm that variations are expected. In the analyzed case study, it emerges that, on average, the long-term evolution of the wave climate shows a tendency toward intensification, while a decrease in the frequency of calm conditions is estimated. The average annual number of events undergoes an increase. Moreover, changes in wave directional sectors are observed, which, from being unimodal, are estimated to exhibit bimodal characteristics in particular on the west coast of the island.

Commercial hatchery processing may affect susceptibility to stress in laying hens.

Directly upon hatching, laying hen chicks are exposed to multiple stressful events during large-scale hatchery processing, which may affect their later coping abilities. Commercial hatchery chicks (HC) were compared to chicks that were incubated and hatched simultaneously under calm conditions (CC). After being raised under similar, non-stressful conditions for 36 days, all chicks were exposed to a series of stressors: transportation and introduction into a novel environment followed by a regrouping event in order to characterize long-lasting consequences of hatchery treatment. Tonic immobility, corticosterone levels, and peripheral body temperature were used to assess reactions to the stress events. Tonic immobility was not affected by treatment but was significantly reduced in CC after transport. Corticosterone levels did not differ between treatments when assessed two days before and two days after regrouping. Comb temperature was significantly higher in HC following regrouping, indicating stress-induced hyperthermia. Furthermore, comb temperature dropped more following blood sampling in HC than in CC, indicating a stronger autonomic response to acute stress. In conclusion, the results suggest possible long-term negative effects of commercial hatchery processing, compared to hatching under silent and less stressful conditions, on the coping ability of laying hens to later stressful experiences.

Measurement and Calibration of Regulatory Credit Risk Asset Correlations

Vasicek’s asymptotic single risk factor (ASRF) model is employed by the Basel Committee on Banking Supervision (BCBS) in its internal ratings-based (IRB) approach for estimating credit losses and regulatory credit risk capital. This methodology requires estimates of asset correlations; these are prescribed by the BCBS. Practitioners are interested to know market-implied asset correlations since these influence economic capital and lending behavior. These may be backed out from ASRF loan loss distributions using ex post loan losses. Prescribed asset correlations have been neither updated nor recalibrated since their introduction in 2008 with the implementation of the Basel II accord. The market milieu has undergone significant alterations and adaptations since then; it is unlikely that these remain relevant. Loan loss data from a developed (US) and developing (South Africa) economy spanning at least two business cycles for each region were used to explore the relevance of the BCBS calibration. Results obtained from three alternative methodologies are compared with prescribed BCBS values, and the latter were found to be countercyclical to empirical loan loss experience, resulting in less punitive credit risk capital requirements than required in market crises and more punitive requirements than required in calm conditions.

The effect of weather conditions on scores at the United States Masters golf tournament.

This paper investigates the sensitivity of golfers' performance to meteorological conditions at the men's US Masters tournament over the 40-year period 1980-2019. The mean and standard deviation of round scores are related to local temperature, humidity, wind speed and direction, and concurrent and antecedent precipitation. Mean scores are more dependent on weather conditions than the variability of scores in a given round. The best predictor of mean scores is the wet-bulb temperature in rounds one and two, and the zonal wind speed in rounds three and four. Across both sets of rounds (1 and 2, and 3 and 4), the wet-bulb temperature is a better predictor of mean scores than the air temperature, which implies that atmospheric moisture content affects scores. In general, golfers take fewer shots and so perform better in warmer and calmer conditions. The synergestic effect of several weather variables explains over 44% of the variance in mean scores. Mean meteorological conditions during play are a much better predictor of the players' average performance than the standard deviation of the weather variables. The golfers' performance becomes more variable in cooler conditions with a wider range of scores. Precipitation during play and the dampness of the ground (as quantified by rainfall up to ten days before play) do not have a consistent and statistically significant effect on the competitors' performance. In short, this paper demonstrates that golf scores are dependent on weather conditions.

Honeybee flight dynamics and pair separation in windy conditions near the hive entrance

Animals and living organisms are continuously adapting to changes in their environment. How do animals, especially those that are critical to their ecosystem, respond to rapidly changing conditions in their environment? Here, we report on the three-dimensional trajectories of flying honeybees under calm and windy conditions in front of the hive entrance. We also investigate the pitch and yaw in our experiments. We find that the mean velocities, accelerations and angular velocities of honeybees increase with increasing wind speeds. We observed that pair separation between honeybees is highly controlled and independent of wind speeds. Our results on the coordination used by honeybees may have potential applications for coordinated flight of unmanned aerial vehicles.

NUMERICAL ANALYSIS OF MODIFIED ANGLE OF ENTRANCE AND DUCKTAIL ADDITION OF THE 1,500 GT RO-RO FERRY HULL VALIDATED WITH SHIP MODEL RESISTANCE TEST

The main problem of ferry ships is maintaining the speed due to ship resistance. There are many efforts to reduce the resistance by modifications of them. This study aims to reduce resistance due to modification of the hull form on the bow Angle of Entrance (AoE) and ducktail addition at the transom stern. The object of the research is a 1,500 GT ro-ro ferry. The AoE minimizes wave resistance and improves flow patterns, while the ducktail reduces the negative effects of the circulation zone on the wetted transom so that waves and wake are reduced. Computational Fluid Dynamics (CFD) was used to analyze these modifications. The final results of the numerical simulation are then verified by the ship model resistance test in the towing tank. Tests were conducted in calm water conditions at a draft of 3.30 meters with a speed variation of 10 - 18 knots. The results show that with the combination of AoE and Ducktail, at ship speeds of 13 to 18 knots, the reduction in resistance from CFD ranges from 13.13% - 16.69% while the experimental results range from 16.00% - 16.54%. While separately the AoE modification is between 8.89% – 12.19% and ducktail is 3.12% -3,62%.

Towards Estimating Probability of Fish–Turbine Encounter: Using Drifters Equipped with Acoustic Tags to Verify the Efficacy of an Array of Acoustic Receivers

An area has been designated for demonstrating the utility of marine hydrokinetic turbines in Minas Passage, Bay of Fundy. Marine renewable energy may be useful for the transition from carbon-based energy sources, but there is concern for the safety of fish that might encounter turbines. Acoustic receivers that detect signals from acoustically tagged fish that pass through the tidal demonstration area and the detection efficiency of tag signals might be used to estimate the likelihood of fish encountering marine hydrokinetic turbines. The method requires that tagged fish passing through the development area will be reliably detected by a receiver array. The present research tests the reliability with which passing tags are detected by suspending tags beneath GPS-tracked drifters. Drifters carrying high residency Innovasea tags that transmitted every 2 s were usually detected by the receiver array even in fast currents during spring tides but pulse-position modulation tags were inadequate. Sometimes very few high residency tag signals were detected when fast tidal currents swept a drifter through the receiver array, so increasing the transmission interval degrades performance at the tidal energy development area. High residency tags suspended close to the sea surface were slightly less likely to be detected if they passed by during calm conditions. Previously measured detection efficiencies were found to slightly overestimate the chances of a high residency tag carried by a drifter being detected as it passed by a receiver. This works elucidates the effectiveness with which acoustically tagged fish are detected in fast, highly turbulent tidal currents and informs the application of detection efficiency measurements to calculate the probability that fish encounter a marine hydrokinetic turbine.

On the Partial Calmness Condition for an Interval-Valued Bilevel Optimization Problem

On the Partial Calmness Condition for an Interval-Valued Bilevel Optimization Problem

Turning and zigzag maneuverability investigations on a waterjet-propelled trimaran in calm and wavy water using a direct CFD approach

The evaluation of ship maneuverability characteristics typically involves the mode tests, direct CFD computations, and system-based simulations. The three methods have been widely used in traditional vessels. However, the trimarans, which are appended with the waterjet propulsion systems, have been rarely researched and assessed comprehensively based on the above methods. This paper used a free-running waterjet-propelled trimaran model test to obtain the constant turning and zigzag maneuvering performance in calm water conditions. By embedding the speed and heading controllers in a CFD program, along with the region moving method, a direct free-running maneuvering CFD model was established on a waterjet-propelled trimaran. Compared to the free-running model tests, the simulation results indicated that an empirical hydrodynamic derivative-based Maneuvering Model Group (MMG) method produced the fastest results but lacked accuracy in simulating a constant turning diameter, making it suitable for fast maneuvering estimation and prediction during the design stage. Conversely, a direct force (moment)-based CFD model required more accurate input estimates to acquire acceptable simulated results. Meanwhile, a body force-based CFD model considered more complex nonlinear impacts and was most similar to reality, achieving better agreement with the experimental results. Additionally, the simulations of the direct free-running maneuvering CFD model in calm and wavy water proved advantageous in examining hull-propulsor interaction during physically similar maneuvering processes where the model test was inadequate.

A novel CFD approach for the prediction of ride control system response on wave-piercing catamaran in calm water

Ride Control Systems (RCS) on high-speed vessels help improve passenger comfort and mitigate dynamic structural loads. Incat Tasmania Wave-Piercing Catamarans (WPC) use RCS consisting of a central T-foil, and a stern tab on each deli-hull. Previous towing tank studies on a 2.5 m model of a 112 m WPC have demonstrated significant reductions in motions with the use of a T-foil and stern tabs. To extend this work, this study examines the use of Computational Fluid Dynamics (CFD) to predict the ship's response with RCS implemented. The model-scale WPC was simulated in calm water conditions, traveling at 2.89 m/s (Fr∼0.6), with step responses applied at the T-foil and stern tabs, to determine the trim and sinkage. The T-foil was implemented in CFD using two methods: 1) Overset mesh; 2) Forcing function. By replacing the geometric mesh with a lift force coefficient and forcing function, the setup difficulty and computational cost were reduced. Only about 7% difference was observed between CFD and experiments, but no significant difference was found between the methods of overset mesh and forcing function. This has proven the ability of CFD to predict vessel responses to RCS step changes in calm water, and the simplified forcing function method is recommended.