MassFLOW-3DTM as a simulation tool for turbidity currents: some preliminary results - From Depositional Systems to Sedimentary Successions on the Norwegian Continental Margin - page 593

Velocities physical experiments

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Velocities numerical experiments

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Sediment concentrations numerical experiments

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Fig. 4. Comparing numerical (Fig. 4B) and physical (Fig. 4A) experiments of the head of the turbidity current. Flow direc-
tion is from left to right. Magnitudes of the numerical 2D velocities are indicated by colours (see colour bar on the right).
Horizontal time axis is replaced to indicate distance by multiplying the time values by an average head propagation veloc-
ity (0.3 m s −1 ). Fig. 4C shows the sediment concentration at the head of the turbidity current, displaying how its shape
matches well to the shape from the physical observation shown in Fig. 4A.

that height, the velocity falls below 0.15 m s −1 at
about 10 cm above the flume floor. For all numerical
simulations the peak velocity is slightly lower than
that observed in the physical experiments (approxi-
mately 3 cm s −1 , or 3%, slower). Furthermore, the
highest velocity values in the physical experiments
are located at a lower level than the numerical
simulations (approximately 3 mm, approximately
equal to the ∆Z of the computational mesh). The
error between simulated cases and physical experi-
ments is lower than 7% at all elevations. It is
important to note that this misfit may be ascribed
to either remaining uncertainties regarding param-
eters of the model or to experimental uncertainties.
These experimental uncertainties could be due to
a fluctuating flow discharge in the piping system,
small imperfections in the measurement of the
inlet size, unequal roughness of the sand glued to
the flume floor, minor deviation of the grain size
difference from the mean grain size (only a single
grain size is used in the numerical simulations and
not a distribution around d 50 ) and inaccuracies in

UVP Average Velocity Profile in the Body of the Current

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UVP Velocity Profile

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Velocity (ms -1 )

Fig. 5. The measured velocity profile of physical Case Ib.