A Conceptual Model refers to a basic, highlevel representation of the hydrogeological system being modeled. It will form the foundation for one or more numerical models. In Visual MODFLOW Flex, the conceptual model is completely grid and simulator independent. This means you define the inputs using your raw data objects (surfaces, polylines, polygons, etc.). The grid or mesh is only introduced at the time of launching a numerical model. This allows you to:
•Convert the conceptual model to multiple numerical models for uncertainty analysis
•Convert the conceptual model to a MODFLOW or FEFLOW model
•Easily update corresponding numerical models as your conceptualization changes
The sequential step in building the conceptual model are presented in the workflow navigator and are summarized below:
2.Collect Data Objects 3.Define the Conceptual Model Area 4.Define Model Structure 5.Define Property Zones 6.Define Boundary Conditions 7.Select Grid Type: Define Finite Difference Grid, Define Finite Element Mesh, or Define UnStructured Grid 8.Convert to Numerical Model 9.Translate to Finite Element Model 10.Convert to Unstructured Model 

When a new conceptual model is created, a new Model Explorer tree is added to the Conceptual Model Explorer in the main Visual MODFLOW Flex window.
The Model Explorer tree consists of a fixed folder structure that is designed to guide you through the workflow of building your conceptual model.
Before You Start! 
If you need to create, modify, or maintain a model that utilizes any of the following features, you must continue to use Visual MODFLOW Classic interface for this:
➢Flow Engines (MODFLOW96) ➢Flow Packages (ETS1, MNW, STR) ➢Transport Engines (MT3D99, PHT3D) ➢MGO 
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