Besides the 2D and 3D visualization tools available within the software, EEMS now writes your model results straight into a Tecplot dataset including water column variables, grid, node values and the velocity vectors. This blog explains how to configure and execute exports using the EEMS export tool, alongside the underlying file architecture that governs transient Tecplot datasets.
Lake Washington Ship Canal Example
The animation below was generated using Tecplot data extracted from the Lake Washington Ship Canal model developed by DSI. In this application, two separate data files were extracted: 1) Velocity vectors dataset; 2) Temperature results dataset. The two data files were then appended in Tecplot to create the final combined animation.
Exporting from EEMS
The “Export Model Results to Tecplot” dialog shown in Figure 1 accessible through tools in EEMS can be used to export model outputs to a Tecplot 360-supported .plt format.
Figure 1 - Export Model Results to Tecplot in EFDC+ Explorer.
| CONTROL | WHAT IT DOES | |
|---|---|---|
| 1 | Parameters to Extract | Your export list. < adds, > removes, Up/Dn reorder and that order becomes the VARIABLES line. |
| 2 | Plot Type / Primary Group / Parameter | Plot Type sets the spatial form of the zones, and in 2D adds a Z selector. Primary Group narrows to a module; Parameter picks the constituent within it. |
| 3 | Time Series Start / Stop | The export window in model days, with the calendar date echoed. Time step skip writes every Nth snapshot. |
| 4 | Grid Options | All cells, or only those inside your polygons. Clip to a reach and the rest is left out of the file entirely. |
| 5 | Export Options | ASCII or binary, plus the output path. Binary for anything you intend to animate. |
| 6 | Export | Writes the dataset to the path above, ready to load in Tecplot. |
2D or 3D: Switching Plot Type to 2D Cartesian changes what the dialog asks for. Z: selector appears next to it (Figure 2), offering water depth, water elevation or bottom elevation, and Update refreshes the parameter lists to match. In a 3D export Z is the layer geometry; but in a 2D export there is only one surface, and Z selector decides what height it is drawn at.
Figure 2 - In 2D Cartesian mode the panel includes a Z selector.
A Closer Look: What a Tecplot file is
A Tecplot dataset is a list of variables plus a stack of zones. A transient run is simply many zones carrying successive timestamps.
One variable list, many zones. A dataset declares its variables once, at the top, and every zone that follows has to account for all of them, by writing values, by sharing them from an earlier zone, or by declaring them passive. That is why adding one parameter in EEMS costs an array in every snapshot rather than a single column at the end.
Ordered or finite-element. An ordered zone is a structured I×J×K block where connectivity is implied by index order alone. A finite-element zone instead lists its nodes and then spells out which nodes form each element.
Nodes are corners; elements are cells. A cell has four corners in 2D and eight in 3D, but neighboring cells share them, so a grid needs far fewer distinct nodes than it has corner slots. The node list carries each one once; the connectivity table — four node numbers per line for quadrilaterals, eight for bricks — is what lets Tecplot rebuild the mesh from it.
Vectors are just variables. The format has no vector type. Velocity comes out as three scalar components, VelX, VelY, VelZ sitting alongside any scalars you exported, and you tell Tecplot which three to treat as components when you set up the vector plot.
Time is just a stack. Nothing in the format is inherently transient. Each zone carries a timestamp, Tecplot orders the zones by it, and the result is an animation.
| WRITTEN ONCE | File header. TITLE and VARIABLES. A single variable list governs every zone below it. | once |
| ZONE 1 | Grid and values. Zone header, then every node’s X, Y and Z with its parameter values, then the connectivity table. | full size |
| ZONES 2 to N | Values only. Zone header declaring what it shares, then Z and the parameter values. No X, Y, or connectivity table. | ~1/3 as large |
ASCII or binary: Both carry identical information. ASCII is readable with notepad, which makes it right while you are still checking that an export contains what you expected; binary is roughly a third the size and loads far faster, which makes it right for long animations. One naming note: .dat is the conventional ASCII extension and .plt the binary one. EEMS defaults to .plt either way, Tecplot inspects content rather than extension, so the file loads correctly regardless.
| RECORD | WHAT IT CONTROLS | WHAT EEMS WRITES |
|---|---|---|
| VARIABLES | Names and order of every column. | X Y Z then your parameters |
| ZONETYPE | FEQuadrilateral 2D, FEBrick 3D layered, ORDERED plain I×J×K. | FEQUADRILATERAL in 2D, FEBRICK in 3D |
| DATAPACKING | POINT writes one row per node; BLOCK writes one variable at a time and is what cell-centred data requires. | POINT, values written at nodes |
| SOLUTIONTIME | Where the zone sits on the timeline. | Absolute model day, one per zone |
| STRANDID | Groups zones into a single time-varying object. | Not written* |
| CONNECTIVITYSHAREZONE | Reuse the element table from zone 1. | =1 on every zone after the first |
| VARSHARELIST | Reuse chosen variables from zone 1. | ([1,2]=1) - X and Y only |
*Because STRANDID is absent, time is carried entirely by SOLUTIONTIME.
