## 2 Materials and Methods  
### Physical Modeling of Bulk Transfer Pipelines  
#### 2.1.1 Classification of Bulk Transport Characteristics  
Bulk has a variety of conveying forms unlike fluids. Table 1 lists the typical types and characteristics of the BTS. Depending on the transfer characteristics, the transfer methods can be classified as low-pressure dilute-phase and high-pressure dense-phase transfer methods. The transfer method is generally selected according to the physical and chemical properties of the raw materials and products to be transferred.  
The bulk transfer rate depends on five major parameters: the pipe bore diameter, conveying distance, available pressure, conveying air velocity, and properties of the transferred material [12]. In Table 1, the straight and slanting arrows represent all possible pipeline routes devised during the design stage. A straight line would be the best route for an optimum system design and bulk transfer rate. However, a straight line cannot be a feasible route considering the various structures, pipes, and equipment to be installed in drilling vessels. The flow patterns are generally categorized according to the size, shape, and density of the transferred particles as follows [26]:  
* Dilute phase: 20 m/s < v < 40 m/s
* Medium phase: 10 m/s < v < 30 m/s
* Dense phase: 1 m/s < v < 15 m/s.  
[PERSON] was able to develop a phase diagram which was used extensively in the analysis of pneumatic conveying [27]. In the dilute phase, higher energy consumption and system erosion in the pipelines and bends are some of major problems due to the higher velocity of particles [14], and the quantity of transferred particles becomes smaller. In the dense phase, quantity transferred can be highest but the possibility of repeated flow blockage in a pipe system becomes higher due to the lower particle velocity, and severe pipe vibrations are experienced frequently. [PERSON] et al. developed  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Content** & **Conveying System** & **Characteristics** & **Conveying Products** \\ \hline  & & \begin{tabular}{c} High energy \\ consumption \\ High operational \\ reliability \\ \end{tabular} & Wide product range \\ \hline  & \begin{tabular}{c} Dilute phase \\ (strand phase) \\ \end{tabular} & \begin{tabular}{c} Low energy \\ consumption \\ Small pipe size \\ \end{tabular} & Free-flowing powder, fluff, pellets \\ \hline  & \begin{tabular}{c} Slow motion dense \\ phase (slug phase) \\ \end{tabular} & Less dust and streamers & Pellets \\ \hline  & \begin{tabular}{c} Dense phase \\ (fluid phase) \\ \end{tabular} & \begin{tabular}{c} Low energy \\ consumption \\ Small pipe size \\ \end{tabular} & Fluidizable powders \\ \hline  & \begin{tabular}{c} Dense phase with \\ internal bypass \\ \end{tabular} & \begin{tabular}{c} Self-stabilization \\ No plugging \\ \end{tabular} & Partly fluidizable powders \\ \hline  & \begin{tabular}{c} Dense phase with \\ external bypass \\ (slug phase) \\ \end{tabular} & \
\begin{tabular}{c} No plugging \\ Less fines \\ \end{tabular} &
\begin{tabular}{c} Non-fluidizable, \\ cohesive, and abrasive \\ powders \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table}
Table 1: Type and characteristics of BTS [25].  
a way of measuring the wall stress in dense phase flow as well as exploring the structure of dense phase flow with two-dimensional tomographics [9; 28]. In the medium phase, the flow patterns are a mixture of a dilute and dense phase, and the transfer rate can be higher without blockage in a pipe system [12]. Considering the characteristics of the pipelines and materials used in this study, modeling and simulation were performed by using the dilute phase (Table 1).