the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Turbulent features of nearshore wave-current flow
Abstract. Waves and currents influence nearly all nearshore physical processes. Their complex interaction gives birth to complex turbulence features that are far from being completely understood. In this regard, previous studies mainly focused on mean flow or inferred turbulent features from averaged velocities, seldom examining turbulent fluctuations. Moreover, the dynamics of wave-current flow have mostly been replicated in experimental channel setups, i.e. overlooking the natural occurrence of waves and long-shore currents intersecting at a near-orthogonal angle. In the present work, the hydrodynamics of near-orthogonal wave-current interaction is investigated through a physical model study. Experiments were carried out in a laboratory basin in the presence of fixed sand and gravel beds, where current only, waves only and combined flow tests were performed. Flow velocities were measured by means of Acoustic Doppler Velocimeters, through which time-, phase-averaged and turbulent velocities were obtained. Results revealed two main features of the wave-current flow. First, we observed that the superposition of waves do not necessarily induces an increase of the current bed shear stresses. Indeed, depending on bed roughness, wave height and current Froude number, both enhancements or reductions of the current bed shear were observed. Moreover, application of quadrant analysis revealed a periodic evolution of the current turbulent bursts. Specifically, the number of current turbulent ejections-sweeps is reduced or increased as the wave phase progresses from antinodes to nodes and from nodes to antinodes, respectively.
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RC1: 'Comment on egusphere-2024-1730', Xuan Zhang, 19 Jun 2024
This paper presents results of turbulent features in combined wave-current flows, and is of vital significance to coastal scientists and engineers. The manuscript is well-written, and the conclusions are well supported by the evidence as described in experimental results. Therefore, I would suggest this to be published. The conclusions can be modified by listing the number.
Citation: https://doi.org/10.5194/egusphere-2024-1730-RC1 -
AC1: 'Reply on RC1', Massimiliano Marino, 01 Jul 2024
Me and co-authors wish to thank the reviewer for the comments. The conclusions listing were modified to provide quantification to the main findings according to the following:
- Current bed shear is enhanced or reduced by wave motion depending on bed roughness, current freestream velocity and wave orbital velocity, with a maximum current Re* increase of 31% and a maximum decrease of 42%. Decrease of bed shear is induced by the presence of the laminar wave boundary layer, which determines a decrease of shear velocity.
- The current turbulent ejection-sweep mechanism follows an oscillatory pattern determined by the superposition of the wave motion. As the wave boundary layer develops, the number of turbulent bursts progressively increases (up to 47 phase-averaged events) or decreases (up to 16 phase-averaged events) from nodes to antinodes and from antinodes to nodes respectively.
Citation: https://doi.org/10.5194/egusphere-2024-1730-AC1
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AC1: 'Reply on RC1', Massimiliano Marino, 01 Jul 2024
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RC2: 'Comment on egusphere-2024-1730', Anonymous Referee #2, 13 Aug 2024
Dear Authors,
From my viewpoint the work is really nice and it add value to the actual comprehension when considering waves and current interactions. But the final presentation of the work done could be improved, there are some typos and I've had to read some parts of the document several times (maybe it's my English, but an English reviewer could improve the readability of the document).
Typos on
ln 38 (Experiments in a XXXXXX were carried out) ¿ shallow water basin ?
ln 58 (The bottom of the XXXXXX is horizontal and made of soft concrete)
ln 107 (respectively in the x, y and v' directions) v' should be z
ln 111 (to account the incidence) a for is missing
ln 123-125 really difficult to understand, redo please
Other minor issues:
I understand that experimental numbers of table 1, have been done when considering timely order, but it makes more difficult to compare similar cases (1 vs 28). Next time re-order the lab experiments to fit within the logical comparison of the reader.
ks equivalent roughness in ln 161 is obtained from best fitting, but in line 172 is obtained through its intercept. Please clarify the discrepancy and unify the document text
Why figure 2 is presented in vertical configuration of z/h it just make it more difficult to understand the z distance of each measurement to the floor. If it has been made to unify the figures with Figure 3, the distance to the bottom (z) could be included in the right axis of figure 2.
ln 200 I did not understand at the beginning the reasoning for a weaker current, include some reference to the fact that this cases are run with a larger water level.
The only real comment refers to the data presented. The paper focus on the effect over turbulence of adding wave to the existing current and the reduction of turbulence bursts and increase of its intensities. It would be relevant to quantify this changes when considering the wave+current. The presented data (Figure 6) is accompanied by one number and the sentence (This occurrence was observed for all the runs with larger wave height cases, but not easily recognizable for the cases with lower H, ln 274). From my viewpoint that effect should be quantified, so that later on researchers can compare their results and add on their values to study trends under similar/different conditions.
Citation: https://doi.org/10.5194/egusphere-2024-1730-RC2 -
AC2: 'Reply on RC2', Massimiliano Marino, 05 Sep 2024
Me and co-authors would like to thank Reviewer 2 for their comments, suggestions and insights, by which the manuscript is significantly improved. Please find enclosed the point-by-point response to reviewer’s comments in pdf.
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RC3: 'Reply on AC2', Anonymous Referee #2, 06 Sep 2024
Thanks Max for accepting and implementing the changes. good work on a complex subject with little data available.
Citation: https://doi.org/10.5194/egusphere-2024-1730-RC3 -
AC3: 'Reply on RC3', Massimiliano Marino, 15 Sep 2024
Thank you for your thoughtful words and insightful feedback, which have contributed to a substantial improvement of the manuscript.
Citation: https://doi.org/10.5194/egusphere-2024-1730-AC3
-
AC3: 'Reply on RC3', Massimiliano Marino, 15 Sep 2024
-
RC3: 'Reply on AC2', Anonymous Referee #2, 06 Sep 2024
-
AC2: 'Reply on RC2', Massimiliano Marino, 05 Sep 2024
Status: closed
-
RC1: 'Comment on egusphere-2024-1730', Xuan Zhang, 19 Jun 2024
This paper presents results of turbulent features in combined wave-current flows, and is of vital significance to coastal scientists and engineers. The manuscript is well-written, and the conclusions are well supported by the evidence as described in experimental results. Therefore, I would suggest this to be published. The conclusions can be modified by listing the number.
Citation: https://doi.org/10.5194/egusphere-2024-1730-RC1 -
AC1: 'Reply on RC1', Massimiliano Marino, 01 Jul 2024
Me and co-authors wish to thank the reviewer for the comments. The conclusions listing were modified to provide quantification to the main findings according to the following:
- Current bed shear is enhanced or reduced by wave motion depending on bed roughness, current freestream velocity and wave orbital velocity, with a maximum current Re* increase of 31% and a maximum decrease of 42%. Decrease of bed shear is induced by the presence of the laminar wave boundary layer, which determines a decrease of shear velocity.
- The current turbulent ejection-sweep mechanism follows an oscillatory pattern determined by the superposition of the wave motion. As the wave boundary layer develops, the number of turbulent bursts progressively increases (up to 47 phase-averaged events) or decreases (up to 16 phase-averaged events) from nodes to antinodes and from antinodes to nodes respectively.
Citation: https://doi.org/10.5194/egusphere-2024-1730-AC1
-
AC1: 'Reply on RC1', Massimiliano Marino, 01 Jul 2024
-
RC2: 'Comment on egusphere-2024-1730', Anonymous Referee #2, 13 Aug 2024
Dear Authors,
From my viewpoint the work is really nice and it add value to the actual comprehension when considering waves and current interactions. But the final presentation of the work done could be improved, there are some typos and I've had to read some parts of the document several times (maybe it's my English, but an English reviewer could improve the readability of the document).
Typos on
ln 38 (Experiments in a XXXXXX were carried out) ¿ shallow water basin ?
ln 58 (The bottom of the XXXXXX is horizontal and made of soft concrete)
ln 107 (respectively in the x, y and v' directions) v' should be z
ln 111 (to account the incidence) a for is missing
ln 123-125 really difficult to understand, redo please
Other minor issues:
I understand that experimental numbers of table 1, have been done when considering timely order, but it makes more difficult to compare similar cases (1 vs 28). Next time re-order the lab experiments to fit within the logical comparison of the reader.
ks equivalent roughness in ln 161 is obtained from best fitting, but in line 172 is obtained through its intercept. Please clarify the discrepancy and unify the document text
Why figure 2 is presented in vertical configuration of z/h it just make it more difficult to understand the z distance of each measurement to the floor. If it has been made to unify the figures with Figure 3, the distance to the bottom (z) could be included in the right axis of figure 2.
ln 200 I did not understand at the beginning the reasoning for a weaker current, include some reference to the fact that this cases are run with a larger water level.
The only real comment refers to the data presented. The paper focus on the effect over turbulence of adding wave to the existing current and the reduction of turbulence bursts and increase of its intensities. It would be relevant to quantify this changes when considering the wave+current. The presented data (Figure 6) is accompanied by one number and the sentence (This occurrence was observed for all the runs with larger wave height cases, but not easily recognizable for the cases with lower H, ln 274). From my viewpoint that effect should be quantified, so that later on researchers can compare their results and add on their values to study trends under similar/different conditions.
Citation: https://doi.org/10.5194/egusphere-2024-1730-RC2 -
AC2: 'Reply on RC2', Massimiliano Marino, 05 Sep 2024
Me and co-authors would like to thank Reviewer 2 for their comments, suggestions and insights, by which the manuscript is significantly improved. Please find enclosed the point-by-point response to reviewer’s comments in pdf.
-
RC3: 'Reply on AC2', Anonymous Referee #2, 06 Sep 2024
Thanks Max for accepting and implementing the changes. good work on a complex subject with little data available.
Citation: https://doi.org/10.5194/egusphere-2024-1730-RC3 -
AC3: 'Reply on RC3', Massimiliano Marino, 15 Sep 2024
Thank you for your thoughtful words and insightful feedback, which have contributed to a substantial improvement of the manuscript.
Citation: https://doi.org/10.5194/egusphere-2024-1730-AC3
-
AC3: 'Reply on RC3', Massimiliano Marino, 15 Sep 2024
-
RC3: 'Reply on AC2', Anonymous Referee #2, 06 Sep 2024
-
AC2: 'Reply on RC2', Massimiliano Marino, 05 Sep 2024
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