Tunnels
The PlaxFlow program offers a convenient option to create circular and non-circular tunnels using arcs and lines.
Drains
Drains are used to prescribe lines inside the geometry model where pore pressures are set to zero.
Wells
Wells are used to prescribe points inside the geometry model where a specific discharge is subtracted from (sink) or added to (source) the soil.
Screens
Screen elements are used to simulate an impermeable screen. An active screen is fully impermeable (separation of pore pressure degrees-of-freedom of node pairs). An inactive screen is fully permeable (coupling of pore pressure degrees-of-freedom of node pairs).
Automatic mesh generation
PlaxFlow allows for automatic generation of unstructured 2D finite element meshes composed of 3-node triangular elements, with options for global and local mesh refinement. For compatibility with the Plaxis deformation program, 6-node and 15-node elements can also be chosen.
Graphical input of geometry models
The input of soil layers, structures, construction stages and boundary conditions is based on convenient CAD drawing procedures, which allows for a detailed modelling of the geometry cross-section. From this geometry model, a 2D finite element mesh is easily generated.
Calculation features
Time dependent conditions
PlaxFlow allows for conditions that are gradually changing in time. Time-dependent conditions can be defined by a linear or harmonic function or by means of an input table.
Steady-state and transient flow
Multiple calculation phases may be created in which different sets of boundary conditions can be specified. The groundwater flow calculation kernel allows for steady-state and transient groundwater flow calculations.
Boundary Conditions
Inflow and outflow
These conditions can be used to specify a recharge or discharge directly on individual boundary lines.
Precipitation
Precipitation is a vertical infiltration that can be used to simulate weather conditions. Infiltration, is a conditional inflow, which can also be specified directly on individual boundary lines.
Closed flow boundary
A closed flow boundary is an object that can be placed at the boundary of the geometry model to ensure that flow across that boundary will not occur.
Water level
General groundwater heads or pore pressures and external water pressures can be conveniently generated on the basis of water levels. Groundwater heads and pore pressures can also be specified directly in individual boundary lines.
Output features
Animations
Video animations can be created for all graphical output quantities.
Curves
Curves can be drawn of selected points in the geometry and of cross-sections. These curves visualise the development of the groundwater head, pore pressure, degree of saturation or Darcy flux during the various calculation phases, which gives valuable insight in the groundwater flow process.
Cross sections
Cross-sections can be used to create graphs for pressures, heads, and flow velocities in any desired cross-section of the geometry.
The PlaxFlow postprocessor has enhanced graphical features for displaying computational results, such as distributions of the groundwater head, pore pressure, degree of saturation and Darcy flux. Values of these quantities can be obtained from the output tables. Plots and tables can be send to output devices or to the Windows® clipboard to export them to other softwares.
Material models
User-defined models
Experts on groundwater flow modelling may enter all parameters of the Van Genuchten model manually or specify userdefined relationships between groundwater head, permeability and saturation.
Predefined data sets
Various types of soil can be conveniently selected on the basis of common soil classification systems (Hypres, USDA, Staring). Predefined data sets for the Van Genuchten and the Approximate Van Genuchten model are available for all types of soil.
Van Genuchten model
Soil can be modelled at several levels of sophistication. Clearly, the number of model parameters increases with the level of sophistication. The Van Genuchten model is a well-known and widely accepted model to simulate unsaturated soil behaviour. This model is one of the models that are available in PlaxFlow.
Material database
Material properties for soil are entered in data sets, which are collected in the project database. Material data sets from the project database may be assigned to individual soil layers.
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