intro story Coast / Estuary

Coast / Estuary

Coastal systems are among the most dynamic physical systems on earth and are subject to a large variety of forces. The morphodynamic changes occurring to coastlines worldwide are of great interest and importance. These changes occur as a result of the erosion of sediments, its subsequent transport as bed load or suspended load, and eventual deposition. 
 
Estuaries are partly enclosed water bodies that have an open connection to the coast. Estuaries generally have one or more branching channels, intertidal mudflats and/or salt marshes. Intertidal areas are of high ecological importance and trap sediments (sands, silts, clays and organic matter).
Within the Delft3D modelling package a large variation of coastal and estuarine physical and chemical processes can be simulated. These include waves, tidal propagation, wind- or wave-induced water level setup, flow induced by salinity or temperature gradients, sand and mud transport, water quality and changing bathymetry (morphology). Delft3D can also be used operationally e.g. storm, surge and algal bloom forecasting. 
 
On this discussion page you can post questions, research discussions or just share your experience about modelling coastal and/or estuarine systems with Delft3D FM. 
 

** PLEASE TAG YOUR POST! **

 

 

Sub groups
D-Flow Flexible Mesh
DELWAQ
Cohesive sediments & muddy systems

 

 

Message Boards

Delft3D PART(oil) issue with sticking (beaching)

EN
Eric Nardi, modified 5 Years ago.

Delft3D PART(oil) issue with sticking (beaching)

Youngling Posts: 2 Join Date: 5/12/11 Recent Posts
Hello everyone,

I am working on an oil spill project using Delft3D-PART(oil) module for the simulations.

Recently, I’ve been running deterministic simulations with controlled conditions (constant wind), and I noticed that some simulations were lacking the sticking portions of the total oil mass. I noticed that only floating oil was present during these simulations, dispersion was negligible in those cases.

Based on the description provided in the manual, I understand that for dispersion to occur the wind speed must exceed 5 m/s. The formulation assumes that white capping occurs only above this limit. This explained why there was no dispersed oil.
However, I am still questioning why (floating) oil is not sticking. Right at the beginning of the simulation the majority of particles go straight towards the land/coastline, and some sticking only occurs when the wind exceeds 5m/s (dispersed oil is present). If the wind is less than 5 m/s (say 4,9 m/s) no sticking occurs.

When comparing the results of the simulations in which the wind was above and below 5m/s, I noticed that the particles that stick are only those that were dispersed and reached the seabed. When the wind is weak, no dispersion occurs, and hence no sticking occur.
The manual says that sticking occurs when particles reach the land by wind effects or horizontal dispersion, and when reaching the seabed by vertical dispersion. But the results indicates that only the sticking due to vertical dispersion and the dispersed fraction touching the seabed is occurring.

Is this behavior expected? Has anyone ever had a similar experience?

Thank you

Eric
U
Frank Kleissen, modified 5 Years ago.

RE: Delft3D PART(oil) issue with sticking (beaching) (Answer)

Hi Eric,
I work at Deltares and work with PART quite a lot. What you describe is not quite what one would expect from PART's behaviour. Your description of what is happening appears to indicate that particles do not stick to the coastline but only to the bed. This in itself is strange because it is governed by the same 'sticky' parameter. This parameter should be greater than 0. If you try 1 then all particles that hit the landboundary should stick. Particles in the oil model can also only stick to a closed model boundary, since that is seen as a landboundary. With a windspeed <5m/s the oil particles (floating) that hit the coastline should stick when the governing parameter equals 1. Without more detail of the model and/or input file it is difficult to pinpoint exactly what your described behaviour is caused by. But I would certainly check on how the model responds when changing the sticky parameter. One other thing: did you have the sedimentation/erosion process switched on? This may make things a little more complex.

Frank