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overestimates the experimental values by up to 5.6% depending on the respective
experimental conditions. It is worth noting that the terminal rise velocity of a droplet is higher at ambient pressure than that of an equally sized droplet at high pressure. This can be explained by the higher compressibility of crude oil as compared
to water leading to a smaller density difference at elevated pressure. Also, the rise
velocity is higher in seawater than in deionized water because of the higher density
difference in the former case. For instance, a 2 mm LSC droplet at a pressure of
12.1 MPa has a terminal rise velocity of about 0.069 m/s in seawater and of about
0.065 m/s in deionized water. A 1 mm LSC oil droplet would have a rise time of
approximately 13.44 hours through 1.5 km of water column corresponding the
depth of the Deepwater Horizon (DWH) blowout at a mean rise velocity of 0.031 m/s
(Pesch et al. 2018).
A modified setup (see Fig. 5.2) is applied in order to capture the oil droplets over
any desired time period, setting pressure gradients to simulate a droplet’s ascent
from the deep sea to shallower depths and finally to the sea surface. Inside the highpressure cell, an hourglass-shaped glass tube is positioned between the observation
windows. A gear pump is applied to generate a laminar downward circular flow of
artificial seawater inside this tube in order to fix a single oil droplet in a vertical
position beneath the tapering of the tube. A cooling circulator is used to adjust the
desired temperature. The droplet’s size and shape are captured against the light
using a high-speed camera and are evaluated automatically with the aid of the image
Fig. 5.2 Experimental high-pressure facility for the investigation of the oil droplet rise behavior
in countercurrent flow with oil presaturation at Hamburg University of Technology. The shown
setup corresponds to the flow diagram in Fig. 5.4 without the part inside the dashed box
S. Pesch et al.
overestimates the experimental values by up to 5.6% depending on the respective
experimental conditions. It is worth noting that the terminal rise velocity of a droplet is higher at ambient pressure than that of an equally sized droplet at high pressure. This can be explained by the higher compressibility of crude oil as compared
to water leading to a smaller density difference at elevated pressure. Also, the rise
velocity is higher in seawater than in deionized water because of the higher density
difference in the former case. For instance, a 2 mm LSC droplet at a pressure of
12.1 MPa has a terminal rise velocity of about 0.069 m/s in seawater and of about
0.065 m/s in deionized water. A 1 mm LSC oil droplet would have a rise time of
approximately 13.44 hours through 1.5 km of water column corresponding the
depth of the Deepwater Horizon (DWH) blowout at a mean rise velocity of 0.031 m/s
(Pesch et al. 2018).
A modified setup (see Fig. 5.2) is applied in order to capture the oil droplets over
any desired time period, setting pressure gradients to simulate a droplet’s ascent
from the deep sea to shallower depths and finally to the sea surface. Inside the highpressure cell, an hourglass-shaped glass tube is positioned between the observation
windows. A gear pump is applied to generate a laminar downward circular flow of
artificial seawater inside this tube in order to fix a single oil droplet in a vertical
position beneath the tapering of the tube. A cooling circulator is used to adjust the
desired temperature. The droplet’s size and shape are captured against the light
using a high-speed camera and are evaluated automatically with the aid of the image
Fig. 5.2 Experimental high-pressure facility for the investigation of the oil droplet rise behavior
in countercurrent flow with oil presaturation at Hamburg University of Technology. The shown
setup corresponds to the flow diagram in Fig. 5.4 without the part inside the dashed box
S. Pesch et al.