Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering Conference
Shanghai, China, June 5–10, 2022
Copyright © 2022 by the International Society of Offshore and Polar Engineers (ISOPE)
ISBN 978-1-880653-81-4; ISSN 1098-6189

www.isope.org

Estimation of Unsteady Pressure Distribution on Ship Hull Surface in Diﬀraction Problem
by Using Pressure Data Measured at One Position
Kantaro Suzuki1 , Takahito Iida1 , Hidetsugu Iwashita2 , Munehiko Minoura112

Department of Naval Architecture and Ocean Engineering, Osaka University, Osaka, Japan
Department of Transportation and Environmental Systems, Hiroshima University, Hiroshima, JapanABSTRACT

2018) in detail. As physical quantities (e.g. added resistance and waveloads) can be evaluated by pressure distribution, the visualization of themby using pressure obtained in the experiments (Iwashita & Kashiwagi,
2018, Kashiwagi, et al., 2019, Kurniawan, et al., 2020) might be helpful
to determine the local area where inﬂuences on forces are signiﬁcant.

In recent years, the emission of carbon dioxides is restricted such as Energy Eﬃciency Design Index (EEDI), and ship with high propulsion efﬁciency is required. In order to reduce the drag force on the hull, the visualization of pressure on the hull is important because it helps to know
where receives signiﬁcant drag force. However, it is not realistic for actual ships to obtain the pressure distribution by using numerous sensors.
Therefore, we develop a method to estimate pressure distribution on theship hull by using pressure data measured at one position. The pressure
distributions in the frequency domain are calculated by the Rankine panel
method. By using the estimated pressure, the impulse response functionsbetween measured pressures and pressures to be estimated are computed.
After this process, the pressures at desired positions are estimated by aconvolution integral. At ﬁrst, the inﬂuence of impulse response function
on the position of the input point is investigated in order to ﬁnd the proper
input position. By setting the input point at the proper position, the unsteady pressure distributions are estimated by using pressure data measured at one position. For the validation of the scheme, the experimentto obtain the pressure distribution was carried out, and the estimated unsteady pressure distributions are compared with the experimental results.
As a result, the estimation by using pressure data at only one position
works well in regular waves from short wavelength to long wavelength.

On the full-scale ship, the analysis by using on-board monitoring datais getting important in order to evaluate the ship performances in actual seas. In the researches, ship performance in actual seas about shaft
power, ship speed, and so on are reported (Orihara & Tsujimoto, 2018,Minoura, et al., 2019). However, the pressure distribution has never beenmeasured on board and has not been discussed. It might be beneﬁcial toobtain pressure distribution on full-scale ships in actual seas because themeasured pressure data can introduce better ship design. In order to satisfy the EEDI or CII, we can propose a new hull shape considering actualseas or speciﬁc ocean, or additional products to reduce drag force by attaching to the hull part where shows big drag force. On the technical side,
the pressure sensor which is assumed as used for ships in actual seas has
been being developed (Hirota, et al., 2021), and the implementation of itis expected. However, it is not realistic to attach numerous sensors to theactual whole hull from the viewpoint of cost and management, unlike theexperiment.
Therefore, we will develop a method to estimate pressure distribution on
the ship hull by using the data measured at one position. In the proposed
technique, the unsteady pressure distributions in the frequency domain
are calculated by the Rankine panel method based on linear potentialtheory. By using the calculated pressure, the relation of the pressure
between at one measured point and at other hull positions is obtained beforehand. This relation is represented by an impulse response function.
The pressure at an unmeasured position is estimated by the convolution
integral with an impulse response function and measured unsteady pressure data as input. Before pressure distribution is estimated, the inﬂuenceof an input point on impulse response functions is investigated. After theinvestigation, the proposed method that the pressure distribution is estimated by time-series data at only one position is validated in diﬀraction
problems in regular waves from short wavelength to long wavelength.
The estimated results are computed with/without consideration of non-KEY WORDS: Unsteady pressure distribution estimation; FBG pressure sensor; impulse response function; seakeeping; Rankine panel
method.

INTRODUCTION
In recent years, the emission of carbon dioxides is restricted such as Energy Eﬃciency Design Index (EEDI), Energy Eﬃciency Existing Ship
Index (EEXI), and Carbon Intensity Indicator (CII). In order to satisfy therules, technology should be developed in various ﬁelds. In seakeeping
study, on the model scale, an innovative experiment measuring the pressure on the whole ship hull surface (Iwashita & Kashiwagi, 2018) wasconducted by using numerous optical type sensors called Fiber BraggGratings (FBG) sensor (Wakahara, et al., 2008). The experiment madeit possible to see local pressure on the ship hull (Iwashita & Kashiwagi,2205