# HydroGeoSphere/Transport

The following instructions affect the I/O for the transport solution.

## Flux output nodes

* new_noutfc Number of new output nodes desired. Read the following new_noutfc times:
       (a) ioutfc Flux output node number.
Listed nodes are flagged to generate detailed mass flux [M T$^{−1}$] information to the file prefixo.flm. For each timestep in the transport solution, one line per flux output node per species will be written to the file which contains the species number, node number, time, concentration, mass flux and nodal coordinates. Such output can be imported into an editor (e.g. Microsoft Excel) and sorted by column to facilitate, for example, the creation of a plot of concentration or flux versus time for a given species at a node.
For an example which uses flux output nodes, see Section 4.5.1.

## Flux output nodes from chosen

This instruction works in a similar way to Flux output nodes except that all currently chosen nodes are flagged as flux output nodes.

## Flux volume output nodes

* fvol_name Descriptive name for the volume up to 40 characters.
Chosen nodes are used to define a volume for which detailed mass flux information will be written to the Tecplot-formatted file prefixo.mass_entering_volume.volume.species.dat, where the prefix, volume and species portions would be the user-defined prefix, volume name and species (i.e. solute) name respectively. For each timestep in the flow solution, one line will be written to the file. Each line contains the time, the average concentration and instantaneous mass flux for all media (i.e. porous, dual, fractured or overland) and the cumulative mass flux for the volume.
Active nodes (the surface of the volume) and contributing nodes (just outside the surface of the volume) are defined automatically by searching for 3-D elements that contain a mixture of chosen and unchosen nodes. For such elements, chosen nodes are flagged as active and unchosen nodes are flagged as contributing.
Mass fluxes reported for the volume are positive if mass is entering the volume and negative if mass is leaving the volume.
In some cases, it may be necessary to restrict the computation of mass flux to a slice of nodes. The following instructions can be used to do this:

## Slice flux output nodes from chosen

* fvol_name Descriptive name for the volume up to 40 characters.
This instruction works in a similar way to Flux volume output nodes except that all currently chosen nodes are flagged as active nodes for the mass flux calculation.
The preceding instruction must be used in conjunction with the following instruction:

## Slice flux contributing nodes from chosen

This instruction flags all currently chosen nodes as contributing nodes for the mass flux calculation.
grok checks that both instructions are issued in the correct order, and that there is at least one element that shares an active and contributing node.

## Plot concentration penetration depth

* threshold_conc Causes HydroGeoSphere to write the distance from domain top to the elevation of the threshold concentration contour versus time to a file called prefixo.penetration_depth.
This is especially useful in conjunction with density-dependent flow simulations where the migration of a dense plume from the domain top into the aquifer versus time is of interest.

## Plot maximum velocity

Causes HydroGeoSphere to write the maximum porous matrix velocity versus time to a file called prefixo.maxvel_pm. If fractures are present, the additional file prefixo.maxvel_fm is created, containing the maximum fracture velocity versus time data.