General Module Function
The modpath_advector module combines MODPATH capability and a tool for sequential positioning of glyphs along the MODPATH lines trajectory to simulate advection of weightless particles through a vector field. The result is an animation of particle motion, with the particles represented as any EVS geometry (such as a jet or a sphere). The glyphs can scale, deflect or deform according to the velocity vector it passes. The direction of travel of streamlines can be specified to be forwards (toward high vector magnitudes) or backwards (toward low vector magnitudes) with respect to the vector field. The input glyphs travel along streamlines (not necessarily visible in the viewer) which are produced by integrating a velocity field using the Runge-Kutte method of specified order with adaptive time steps.
Module Input Ports
The modpath_advector module has four input ports.
The first (leftmost) accepts field data usually from Load_EVS_Field or Read_TCF.
The second port accepts data specifying the starting location of the particle paths, this data is typically generated by a slice, create_grid, isolines or place_glyph module.
The third port accepts any geometry mesh (glyph, usually read in with the load_glyph module) which will be rendered at each starting point and moved sequentially through the vector field during running of the advector module.
The last port is the z exaggeration factor. This input causes the path generation to be calculated in an unscaled system ensuring that velocities are not scaled and are accurate, then scales the position of the paths.
Module Output Ports
Modpath_advector contains four output ports.
The leftmost port outputs a mesh composed of the original mesh plus the meshes representing the particles.
The second output port creates a new unstructured polyline mesh representing the MODPATH lines, and also contains a nodal data component referencing the velocity component.
The third output creates a renderable version of the glyphs.
The fourth output port sends MODPATH polylines to the viewer.
Module Control Panel
The control panel for modpath_advector is shown in the figure above.
Advector options :
The Run toggle starts or stops advection.
The Cycle toggle starts the advection again at Start Time when End Time is reached.
The Reset Time toggle resets Time to the value of Start Time.
The Direction radio buttons control the direction of travel of the glyphs.
The Advection Time slider and type-in allow you to control the particle animation and also display the progress when Run is selected. The time runs from Start Time to End Time during running of advector.
The Advection Time Step type-in allows you to set the duration of each animation step.
The Animation Steps slider controls the incrementation of the glyph stops between the Start Time and the time along the original streamline continuum for each advection step. For example, if the End Time is 10000 and the Animation Steps slider is 10 then there will be ten steps (frames) when the animation is run. The Animation Time Step Type-in box will reflect the time increment based on the slider choice. For the above example (10 steps) the type-in would read 1000.
The Release Cycles slider determines the number of times the particle glyphs will be sent from their release points. This could be thought of as the number of pulses of particle releases. For example, if the End Time is 10000, then a pulse of particles is released at the Start Time and again at 5000.
The End Time slider reflects the time value along the original streamline at which to halt advection of all particles. The default is 1000.0, but the range may be increased to any value. Typically with groundwater flow problems (very low velocities) this number needs to be very large to achieve ample travel distance of particles.
Note that adjustments to either the End Time, Animation Steps, or Animation Time Steps will directly affect one or both of the remaining parameters. For example, adjusting the Animation Time Steps in the above example from 1000 to 2000 would increase the End Time from 10000 to 20000.
The Start Time slider reflects the time value along the original streamline continuum at which to start advection. The default is 0.0
Display Options:
The Scaling Options radio buttons establishes how glyphs are sized based on the data values.
Vector Magnitude sizes the glyphs proportional to the velocity at each node.
Constant Size makes all glyphs the same size.
Log10(Magnitude) scales by the log of the velocity. When velocities span several orders of magnitude working in log space is useful. When selected, an additional parameter is visible:
Magnitude for Zero Size defines the lower clamping velocity that will correspond to a ZERO (0.0) size glyph regardless of "Glyph Scale".
Min/Max Magnitude sets limits on the glyph scale.
The Glyph Scale slider adjusts the sizes of the glyphs. Default range is 0.0 to 100.00, but the type-in box allow for increasing the range to any value. The default scale of 1.00 is approximately 1/100th the x,y extents of the model.
The End percentile slider allows you to control the automatic scaling of glyphs based on the nth percentile value (versus the maximum 100th%). This addresses datasets where there are only a few nodes with extremely high values (like wells).
Z Scalecontrols the z exaggeration factor.
Map Componentselects which MODPATH data component to color the out put lines by.
Model Options:
The DWR File: shows which .dwr/.dwz file has been selected, this file contains MODFLOW package data such as drains, wells, recharge, etc... For details on the DWR file format, see here.
The Time Options radio buttons indicate a time based stopping condition for the particles.
Run to end indicates that the particle will run until it cannot escape a cell due to lack of flow.
Run for date allows a particle to travel from a start date to an end date.
The duration option allows the particles to run for a duration of time in days.
The Sink Options radio buttons indicate stopping conditions for the particles based on the amount of flow through a cell. The Pass through cells with weak sinks option allows all particles to pass through a cell, unless that cell has a strong sink. The Stop in cells with weak sinks button does not allow a particle to pass unless the flow out of a cell is greater than or equal the flow into it. The last option, Stop if discharge to sink is > specified fraction of inflow to cell, allows the user to specify what fraction of inflow will stop particles in that cell. This fraction value is set using the Fraction slider which is visible when the last option is selected. Only values between zero and one are useful.
© 1994-2018 ctech.com