Welcome to the User Interface video series.
This tutorial describes the subdomain graphing functionality available for the
GeoStudio mass and heat transfer products: SEEP/W, TEMP/W, CTRAN/W, and AIR/W.
In GeoStudio, the Draw Graph window provides an effective method for interpreting analysis results.
Element nodes provide convenient locations for plotting most data; however, there are a couple of drawbacks when plotting results at nodes.
Heat and mass flow rates at interior nodes are inherently zero because of conservation requirements.
Nodal data provides no information about stored mass or energy within the domain.
Therefore, flow into a node is equal to flow out of a node, and the divergence in flow is equal to zero.
Consequently, in the past flow rates could only be plotted at nodes where fluid or heat was entering or leaving the domain.
However, the Draw Graph window now includes subdomain graphing of select parameters to overcome these difficulties.
Subdomain graphing allows for the selection of both nodes and optionally, a subdomain, where the subdomain comprises a subset of elements.
The nodes along the edges of a subdomain act as exterior nodes despite being within the larger domain.
Thus, subdomain graphs can be used to plot flow rates or cumulative quantities at interior nodes.
This new functionality replaces flux sections in the flow products,
offers decreased mesh dependency and greater accuracy for interpreting model results,
and provides the ability to plot the results over time.
This GeoStudio analysis considers water flow through an embankment dam.
In the Results view, the Draw Graph window allows for the interpretation of analysis results
with many different parameters available in the dropdown menus.
When plotting mass or heat flow, material properties, and mass or energy balance data
the Set Locations dialogue includes a second tab titled Subdomain.
The Locations tab provides the ability to select nodes, while the subdomain tab allows for the selection of elements.
The corresponding graph shows the results at the chosen nodes given the inputs from the selected elements.
The default setting under the Subdomain tab is to use the entire model domain.
If we were to try to plot water or heat flow at interior nodes given this default setting,
the plotted flow values would be zero.
However, we can define a subset of the domain using one of two available methods.
The first option currently selected in the Set Locations dialogue, allows for the definition of a subdomain adjacent to the selected locations.
We can select the subdomain by holding the mouse down and dragging a box over the desired elements,
or by holding the Shift key and creating a line that goes through the elements,
or finally, by choosing a geometry item.
When we select a subdomain, the flow contributed to the interior nodes from the selected elements is plotted in the Draw Graph window.
If the selected subdomain is not adjacent to the nodes,
then the warning message 'Locations are not on the subdomain' appears in the Draw Graph window.
Also, if the subdomain includes elements on both sides of the selected nodes,
then the plotted flow is negligible for the same reasons as when the entire domain is used for plotting flow at interior nodes.
The second method for defining the subdomain is to use the subdomain cross section selection tool.
By selecting this option, we can draw a polyline, which automatically defines the subdomain and the nodes.
The elements comprising the subdomain are those intersected by the polyline.
Nodes are automatically selected on the left side of the polyline
where the left side is defined relative to the direction that the polyline was drawn.
The subdomain cross section is particularly useful if the required subdomain is irregular.
For example, if we wanted to determine the flow across a section near the toe drain
we can do so by clicking along the desired lines to create the cross section.
We can also plot the change in mass or energy stored within a subdomain.
In a new graph, let us select the Water Mass Balance option from the first dropdown menu
and the Cumulative Change in Domain Water Volume from the second dropdown menu,
and plot this over time.
Under Set Locations, the only tab available in this case is a subdomain tab.
In this graph, I wish to consider the change in water stored within the dam core so I will select the elements representing the core.
Back in the Draw Graph window, I will sum all of the element results and select all time steps.
The plotted results illustrate the decline in water stored within the core over time in this analysis.
Graphing changes in stored volume or mass is crucial to interpreting the results of a simulation
involving an engineered cover system or the transport and attenuation of contaminants.
In summary, subdomain graphs provide increased capability for interpreting results in heat and mass flow analyses.
They offer greater accuracy, decreased mesh dependency,
and the ability to plot flow rate at interior nodes and cumulative mass or energy accumulation over time.
For more information on GeoStudio and its features, please look at the example files and other tutorial videos on the GEO-SLOPE website.
Thank you for watching.