Investigating Airflow Patterns in the XYZ Passenger Ship’s Accommodation Room on the Potential for COVID-19 Exposure to Passengers

The pandemic condition due to the COVID-19 virus attack has affected all areas of life throughout the earth. Post-pandemic policies and new behaviors are one of the important efforts in getting life back to normal. The pandemic has triggered many technological innovations to be carried out as further mitigation and prevention efforts. In the shipping sector, the impact of shipping restrictions and the number of passengers is detrimental due to a decrease in productivity that affects the shipping and port business. Air exchange patterns and room design are important things to be conditioned to reduce the potential for virus exposure. This article presents an investigation of computational fluid dynamics in the accommodation space of the XYZ passenger ship and simulations of potential exposures in several scenarios of ventilation conditions. By simulating 12 models of ventilation conditions, two conditions of the ships being stationary and moving, and the influence of wind from outside. Layout redesign can be applied effectively in open ventilation conditions and has less exposed bench results compared to existing conditions with an effective percentage of 0.75% - 2.3%


Introduction
The pandemic that has lasted for several years has had a significant effect on the shipping industry, especially on passenger ship shipping activities.Covid 19 is one of several types of diseases that are spread through viruses through various media.Transmission is very fast and some variants are very deadly.This virus was first discovered in Wuhan, Chia in December 2019, where most of it lives in the bodies of animals such as bats and snakes.This virus is spread through saliva, or fluids that come out of the mouth along with speaking, sneezing or singing activities [1][2].According to [3] efforts that can be made to slow transmission are by maintaining social and physical distance, maintaining hand hygiene and applying coughing and sneezing ethics.The pandemic that has lasted for several 1250 (2023) 012006 IOP Publishing doi:10.1088/1755-1315/1250/1/012006 2 years has had a significant effect on the shipping industry, especially on passenger ship shipping activities.The covid 19 is one of several types of diseases that are spread through viruses through various media.Transmission is very fast and some variants are very deadly.This virus was first discovered in Wuhan, Chia in December 2019, where most of it lives in the bodies of animals such as bats and snakes.This virus is spread through saliva, or fluids that come out of the mouth along with speaking, sneezing or singing activities.According to [3] efforts that can be made to slow transmission are by maintaining social and physical distance, maintaining hand hygiene and applying coughing and sneezing ethics.
Behavior change according to [4] is also important to prevent the spread of this disease.Several studies conducted regarding the spread of this virus on ships stated that airborne virus transmission took place significantly on ships [5][6] [7], the virus can easily spread from one sufferer into the environment through contaminated air intermediaries due to coughing or sneezing.
According to [8][9][10] [3][11]the process of air ventilation is interpreted as the activity of circulating air from inside the room with outside air with the aim of removing contaminants such as dust, humidity, unpleasant odors, carbon dioxide, hot air, and bacteria in the air.The theory of fluid mechanics is one of the theories that underlie the ventilation process.There are 3 methods of ventilation, namely: 1. Artificial ventilation, namely air exchange with the help of mechanical devices such as supply fans and exhaust fans.2. Natural ventilation, namely air exchange occurs naturally without the help of mechanical devices such as windows or doors.

Combined ventilation, namely natural and natural combined air exchange
The ventilation and air conditioning system for the accommodation is calculated and designed according to the ISO 7547 standard.The general ventilation and air conditioning system is to ensure a good climate for the crew and passengers, while the fresh airflow is related to the number of people but not less than 40% of the total air flow [Romanian Standardization Association.SR ISO 7547, Shipbuilding-Air-Conditioning and Ventilation of Accommodation Spaces on Board Ships-Design Conditions and Basis of Calculations; Romanian Standardization Association: Bucharest, Romania, 2005].Talking about the ventilation system of the accommodation space which is correlated with human activities, natural ventilation systems, and air conditioning are the solutions for comfort.However, related to standards, class rules, IMO and administrative requirements regarding this matter, it should be re-analyzed and revised so that the possibility of spreading the virus can be minimized as much as possible.

Methode
In an effort to anticipate the spread of Covid 19, modifications were made to the passenger ship accommodation space, by first conducting a study of the airflow pattern in the passenger ship accommodation space by using an openclose variation scenario strategy on ventilation.The accommodation space where the passengers gather is assumed to be in 12 ventilation conditions, namely: Table 1.Air exchange simulation conditions in the accommodation space on ship X No.The room parameter data and ventilation used are as follows: The next step is the room design process with CAD, where the room is made in 2D and 3D.For 3D modeling, one fix zone is created.

Figure 1. Modelling
In the Meshing Process, the 3D model is exported into the CFD software as geometry.In this process, naming will also be carried out for the air inlet and outlet areas that blow The final stage of the data analysis process is carried out on the comparison of the contours of the air flow pattern.In addition, the velocity results from the CFD simulation will be used as data for the calculation of hourly air exchange (APCH) in the waiting room.The process of changing the layout of the bench is expected to be a reference in the setting of the accommodation space on natural ventilation.

3.1Open Windows & Open Doors
The following is the flow pattern obtained from numerical calculations with the CFD program From the 4 results, the wind direction from the right has a diffuse airflow and almost all seats are passed by airflow.This can make the passengers feel comfortable in the room.However, there is also concern that the spread of COVID-19 will spread throughout the room due to airflow.

Open Windows and Close Doors
The

Close Windows and Open Doors
The following is the flow pattern obtained from numerical calculations with the CFD program under conditions of closed windows and open doors  When the windows are closed, the results are different from the previous simulation, namely the airflow is more evenly distributed when the wind blows from the left and is most spread out when the ship is moving compared to the wind blowing from the right.

ACPH Calculation
The simulation results also show the inlet velocity in the room so that air exchange per hour (ACPH) calculations can be carried out.From the data obtained from the simulation results, the layout redesign has less exposed bench results compared to the existing where the percentage of effectiveness is 0.75% -2.3%The layout redesigned with closed windows appears to have a higher rate of covid spread than the existing design.This is because the empty area has previously been occupied by chairs, increasing the spread of covid.From the data obtained from the simulation results it is known that the redesigned layout results in more benches being exposed when the subject is in the middle or back with a percentage of -3.7%, while the subject in front has decreased the spread of 5.3%.In the condition where the door was and subject in front area, the flow is different compared to the previous condition, namely the crossing flow is towards the front where the area is empty so there is no spread of covid.As for the middle and back subjects, the flow tends to be straight back and slightly tilted to the left.From the data obtained from the simulation results, it is known that the redesign of the layout has resulted in more exposed benches than the existing conditions where the effectiveness decreases from 0% to -5.3% Based on this work, the velocity is estimated to be Pr = 24.688with an error margin of 2.09% although the error that occurs is quite large, because the domain of the fluid flow is the accommodation space of the ship which can be said to be quite wide, the error can be ignored, because the purpose of this research is not to focus on small things such as pressure but on the distribution of velocity or distribution of flow in a big domains.Besides that the number of elements used is also very large and there are limited resources

Conclusion
The following are some conclusions related to the investigation of airflow patterns in the accommodation space of the XYZ passenger ship with natural ventilation conditions originating only from doors and windows.1.The best ACPH when the window is open and the door is closed when the wind blows from the right is 13 ACPH also meets the standards of the Ministry of Health, namely 12 ACPH and the closed window condition has the lowest ACPH. 2. The position of the suspect determines the number of people exposed, the closer the position of the suspect is to the outlet, the fewer the number of people exposed to the virus.3. Layout redesign can be applied effectively in open ventilation conditions and has less exposed bench results compared to existing with an effective percentage of 0.75% -2.3%

Figure 2 .
Figure 2. Meshing CFD simulation Set Up configuration, Input variable fluid flow (6 m/s, 8 m/s), turbulence model (K-Epsilon Realizable Enhanced Wall Treatment), and outlet pressure (outflow) in CFD simulation.The simulation with the number of calculations per time step which reaches a maximum of 100 iterations.The final stage of the data analysis process is carried out on the comparison of the contours of the air flow pattern.In addition, the velocity results from the CFD simulation will be used as data for the calculation of hourly air exchange (APCH) in the waiting room.The process of changing the layout of the bench is expected to be a reference in the setting of the accommodation space on natural ventilation.

Figure 3 .Figure 4 .
Ship stopped -Right Wind (a) Left Wind (b) Ship in motion -Right Wind (a) Left Wind (b)

Figure 5 .Figure 6 .
following is the flow pattern obtained from numerical calculations with the CFD program under conditions of open windows and closed doors (a) (b) Ship Stopped -Right Wind (a) Left Wind (b) Ship in motion -Right Wind (a) Left Wind (b) Compared to the previous condition where the door was open the flow pattern was not much different.But we can see that there is a difference in the color of the flow which indicates that when the door is closed the velocity is greater than when the door is still open.

Figure 7 .Figure 8 .
Ship stopped -Right Wind (a) Left Wind (b) Ship in motion -Right Wind (a) Left Wind (b)

FromFigure. 9 .
Figure.9.Layout Existing Open Ventsuspect at behind (a) Front (b) Centre (c) In the simulation results in existing with windows and doors open, it can be seen that the flow of the spread of covid tends to be straight back, resulting in people sitting behind the subject being exposed to covid.The following is a layout redesigned simulation with the same subject conditions.

Figure 10 .
Figure 10.Layout Redesigned Open Ventsuspect at behind (a) Front (b) Centre (c) In the redesigned layout, the seat layout has less exposure than the existing condition because the flow of covid spread tends to be straight even though the seating position is changed.

Figure 11 .
Figure 11.Comparison of the number of seats exposed to Covid-19 in existing conditions with layout redesign.From the data obtained from the simulation results, the layout redesign has less exposed bench results compared to the existing where the percentage of effectiveness is 0.75% -2.3%

Figure 12 .
Figure 12.Existing Layout Close Window -Open doorsuspect at behind (a) Front (b) Centre (c) In contrast to the condition of open windows and doors, when the window is closed, the flow of the spread of Covid tends to turn left, no longer going straight back.However, in this condition, the flow tends to pass through empty areas where there are no seats.

Figure 14 .
Figure 14.Comparison of the number of seats exposed to Covid-19 in existing conditionswith layout redesign.From the data obtained from the simulation results it is known that the redesigned layout results in more benches being exposed when the subject is in the middle or back with a percentage of -3.7%, while the subject in front has decreased the spread of 5.3%.

Figure 16 .
Figure 16.Layout Redesigned -Open Vent -Close Doorsuspect at behind (a) Front (b) Centre (c) The redesigned layout with the condition of the closed door has a different flow on the front subject.In this condition, the flow goes backward, causing the number of people exposed to

Figure 17 .
Figure 17.Comparison of the number of seats exposed to Covid-19 in existing conditionswith layout redesign.From the data obtained from the simulation results, it is known that the redesign of the layout has resulted in more exposed benches than the existing conditions where the effectiveness decreases from 0% to -5.3%

Table 2 .
The

Table 3 .
Parameter of Simulation

Table 4 . ACPH Calculation Model Air Exchange perhour (ACPH) Average velocity (m/s) Inlet Area (m2) Volume of Room (m3)
The theoretical convergence order is p=2.0.This difference is most likely due to mesh distortion, mesh quality, solution nonlinearities, turbulence modeling, and other factors.Now the two finest grids are selected and the Richardson extrapolation method are applied to estimate the value of the pressure recovery for zero grid spacing.It is approximately 1, indicating that the solution is within the asymptotic region of convergence.