SRDG April2011
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Brief description of SUNTANS model implementation to research hydrodynamic characteristic of the Pentland Firth
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SRDG April2011
- 1. Stromness, 27 th February 2011 SUNTANS Model Pentland Firth and Orkney Waters Dr. Susana Baston Meira ICIT- International Centre for Island Technology Heriot-Watt University, Orkney Campus
- 5. Introduction to Numerical Flow Models Information in z-coordinate TELEMAC-3D http://www.telemacsystem.com/ SUNTANS S tanford U nstructured N on-hydrostatic T errain following A daptive N avier-Stokes S imulator http://suntans.stanford.edu/ ROMS R egional O cean M odel S ystem http://www.myroms.org/ POM P rinceton O cean M odel http://www.aos.princeton.edu/WWWPUBLIC/htdocs.pom/ MIKE-3D http://mikebydhi.com/Products/CoastAndSea/MIKE3.aspx FVCOM F inite V olume C omunnity O cean M odel http://fvcom.smast.umassd.edu/FVCOM/index.html COHERENS CO upled H ydrodinamic E cological model for RE gio N al S helf Seas http://www.mumm.ac.be/EN/Models/Coherens/index.php ADCIRC A (parallel) AD vanced CIRC ulation model for Oceanic, Coastal and Estuarine waters http://www.unc.edu/ims/adcirc/ 3-D Hydrodynamic Models
- 6. SUNTANS Model: Definition SUNTANS is a numerical model designed for the simulation of complex, non-hydrostatic , coastal, river and estuarine flows, with high resolution on unstructured grids using parallel computers.
- 9. SUNTANS Model: Open Source Why not Mike-3D? Commercial software Why not Telemac? Only 2D open source Why not FVCOM? Non-hydrostatic version yet to be tested Unstructured
- 11. SUNTANS Model: Nonhydrostatic It is ideally suited to modelling regions of high turbulence including density gradients Fringer, O., McWilliams, J. & Street, R., 2006. A New Hybrid Model for Coastal Simulations. Oceanography , 19(1), 65-77. SUNTANS is Non-hydrostatic Solves vertical acceleration and friction
- 12. Implementation: PF & OW Computational requirements Model is installed on the IPE cluster in Edinburgh. It has 10-node of 8 processors. Operating system: Linux Initial conditions : -- Quiescent free surface and velocity field -- No stratification Boundary conditions : They are given by the first eight tidal constituents computed by OTIS 38,342 cells, 20 levels, Δt=2s, Run Time 14 hours, Simulation 3 days, 6 processors
- 13. Implementation: PF & OW 25708 cells, 20 z-levels, Δt=2s, Run Time 12 hours, Simulation 3 days, 4 processors
- 14. Implementation: PF & OW 38342 cells, 10 levels, Δt=5s, Run Time 1 day, Simulation 10 days, 2 processors
- 15. Implementation: PF & OW Point 1 Comparison SUNTANS-OTIS
- 16. Implementation: PF & OW The UKHO provided Gardline with three target locations for the deployments as follows: Data: One month of velocity averaged every 10 minutes 11:35 14/09/01 71 m 002° 58’ 35”W 58° 40’ 13”N 3 12:01 14/09/01 80 m 003° 05’ 09”W 58° 43’ 01”N 2 12:30 14/09/01 82 m 003° 14’ 11”W 58° 43’ 34”N 1 TIME DEPLOYED DEPTH LONGITUDE LATITUDE SITE
- 17. Implementation: PF & OW
- 19. Email: s.baston@hw.ac.uk Web: http://www.icit.hw.ac.uk/ Thanks for your attention!
Notes de l'éditeur
- Good morning everyone and thank you for coming here today. My name is Susana and I’m going to talk about the implementation of SUNTANS model in the Pentland Firth and Orkney Waters.
- First of all, I’d like to introduce people involved in this work. This is myself, Dr Rob Harris and Prof Jon Side from ICIT, Dr Karl Stephen from IPE in Edinburgh campus and Prof Margot Gerritsen from Stanford University (California).
- The structure of my talk will be as follows: A brief introduction to numerical flow modelling Description of SUNTANS model Explain how the model has been implemented at PF&OW And what are the main aims we are looking for
- A hydrodynamic numerical model is a tool to observe, understand and predict physical processes in the ocean and coastal waters. Their main advantage is that they allow study of coastal systems in different scales spatial-temporal, representing a significant savings in field campaigns. B ut to do this, we must be sure about the accuracy of the results, which is generally done by comparing model results to observations. In the MRE field they are useful in: Description of water column structure Estimation of energy resource Evaluation of scales of resolution Study the physical environmental changes And coupled to another numerical models research the shoreline morphodynamic alteration and larvae and pollutants transport Therefore there are an increasing interest in 2D and 3D models implementation
- The difference between a 2D and a 3D model is that the 2D is averaged in depth (assuming that the vertical differences are not important) and 3D models give us detailed information through the whole water column. MRE development needs to know as detailed as possible the flow behaviour from surface to depth, so we need to develop and implement a 3D numerical model. In this table are mentioned some of the most known 3D hydrodynamic models. SUNTANS has been included recently in this list because it had been developed in 2006. Now I’ll explain a little more about it and why we have choose it. ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Why 3D models? MRE is in full swing, many new prototypes will be shortly installed in the sea and we need to know the hydrodynamic conditions in the whole water column because of different designs. Not only to manage the resource but also to predict environmental effects. So, 3D Hydrodynamic Models are the perfect tool to get the information with the resolution that we would need. Where is the problem? First, they are complex (expertise staff is required), second they need a huge computational effort, and last, field measurement are necessary to validate the model.
- SUNTANS comes from… It is ….
- SUNTANS model was first developed to simulate the internal wave field in the littoral ocean. Internal waves may be generated by stratified tidal flows over bottom topographic features. This kind of waves are known as internal tides when they have tidal frequencies. SUNTANS has been applied to Monterey Bay to study the interaction of the tides with the bottom topography and the subsequent generation of internal tides. Publications in 2009 show that it was used to study sediment transport and eddies generation. Last year works are related to turbulent mixing and available potential energy in internal wave fields This quick application in oceanographic research works identify SUNTANS as a strong tool with high potential
- Why SUNTANS? We are using this model because of a collaboration between Institute of Petroleum Engineering of Heriot-Watt University and Stanford University Main advantages of Suntans model are that it is an open source available for academic and research purposes It is tridimensional the unstructured grid provides exceptional resolution around fine-scales features Parallel implementation facilitates high resolution And it includes the non-hydrostatic approximation, which make it deally suited to modelling regions of high turbulence including density gradients .
- Here we have made a comparison of main characteristics of 5 of these models. Telemac, FVCOM, ADCIRC, SUNTANS and Mike-3D. As we can see there are some of them which “a priori” could be more full featured because include Water quality and sediment transport modules. For example, TELEMAC or Mike-3D, but both of them are commercial software. And the advantage of SUNTANS compared to FVCOM or ADCIRC is that the formulation is non-hydrostatic.
- Two classes are common in hydrodynamic models: structured grid approaches (primarily finite difference algorithms) and unstructured grid approaches (including finite element and finite volume methods) . Structured grids take their name from the fact that the grid is laid out in a regular repeating pattern called block. These types of grids use quadrilateral elements in 2D and hexahedral elements (in 3D in a computationally rectangular array). Their advanteich over other sort of grids is that they alau (allow) the user a high degree of control, you can specify deltaex and deltguay. Unstructured grids use elements (cells) without a pattern, and that is because they are called unstructured. These types of grids typically utilize triangles in 2D (and tetrahedra in 3D). The advanteich of unstructured grid is that the meshing algorithm is automatic and, therefore, require little user effort. The drawback (dr óback ) is that unstructured flow solvers typically require more memory and have longer execution times than structured grid solvers on a similar mesh. Terrain following adaptive means that this kind of grid allow for high resolution in localized regions of flows in the vicinity of complex coastlines or embayments. Numerical ocean models could be classified in terms of vertical discretisations ( Discretaiseizons) as being basically ( Beisicli) zet coordinate models, aisopicnal models and sigma coordinate model.
- Effect of computing the lock-exchange problem with a hydrostatic and a nonhydrostatic simulation code. The figure shows how the hydrostatic code captures the large-scale dynamics by correctly computing the position of the front while it fails to capture the formation of the billows because their horizontal length scales are less than the depth, and therefore highly nonhydrostatic. The red fluid represents the salty or heavy fluid, while the blue fluid represents the freshwater or light fluid. Gravitational circulation and the hydrostatic pressure field enforce a recirculating flow field in which the salty, heavy fluid (red) flows beneath the fresh, light (blue). Fringer
- Until now, we have been focused in the Pentland Firth area.
- That is an example of parallel implementation. Grid is splitted to run in four processors in this case, in order to increase the efficiency of computational requeriments.
- Comparison of SUNTANS to the OTIS results demonstrates that the model is working fine, therefore we have a very powerful tool to understand the hydrodynamics in Orkney Waters.
- Fist way to validate the model is comparing the results to the OTIS ones. Comparison of SUNTANS to the OTIS results demonstrates that the model is working fine
- Calibration: comparison of model output to ADCP data
- Comparison of SUNTANS to the OTIS results demonstrates that the model is working fine, therefore we have a very powerful tool to understand the hydrodynamics in Orkney Waters.
- Therefore, there are several arms towards focus the research using SUNTANS model. For example: