New User Guide

The list of topics below represents a “guided tour” of information found in this documentation that, when processed in order, can help the new user quickly develop an understanding of FLAC in its design, capabilities, and use.


The first two topics here are found in the Itasca Software Guide, a major section of this documentation that contains all material shared commonly between the programs FLAC, 3DEC, and PFC. The section on FLAC (FLAC2D/FLAC3D) is limited to material specific to the program. The FLAC user will move back-and-forth between these two major headings when consulting the program documentation.

General Approach

FLAC is numerical modeling software. This topic will provide an overview of the practice, its potential and its limitations.

Solution Procedure

A generalized workflow for problem solution is illustrated here. While FLAC is open-ended software that can be used in myriad ways, the majority of modeling projects will likely follow some or all of this flow.

Tutorial: Quick Start (FLAC2D) (FLAC2D) or Tutorial: Quick Start (FLAC3D) (FLAC3D)

In a hurry to get hands on? These tutorials exist for that exact purpose. Note, along the way, how even the quick tutorials follow the methodology illustrated in “Solution Procedure.”

Tutorial: Illustrative Model — Mechanics of Using FLAC3D

This deeper, more extensive tutorial builds upon the basics illustrated in the “Quick Start” tutorials. Greater exposition and line-by-line description of program commands is provided.


By the time the two tutorials are completed, the new user should have a solid initial grasp on how to work with FLAC.

The next items here represent first stops for a variety of possible avenues of further self-guided exploration. They do not have the same order-dependence as the topics above.

FLAC Examples

A substantial library of example problems is provided on this page. Users who know what kind of problem they’d like to solve may wish to familiarize themselves with the offerings provided here. Note these examples are standalone projects. There are considerably more illustrative examples provided throughout the documentation. Becoming familiar with the FLAC Examples Index is highly recommended. Searching for examples across all topic areas becomes increasingly important as proficiency increases, and this page should become the user’s primary access point for that purpose.

FLAC Commands Index and FLAC FISH Index

By this point the user should have a comfortable familiarity with FLAC as command-driven software. The thorough-minded user may consider a top-to-bottom perusal of the program’s commands and built-in FISH functions. These indexes are optimal starting points for doing so.

Index: Common Commands and Index: Common FISH

The preceding exercise is also recommended for the shared commands and FISH. Note that this familiarization will underline what is meant by “FLAC-specific” and “shared by all Itasca software,” a distinction that is pervasively used throughout this documentation (and see Note above).

FISH Scripting Reference

Using scripting to customize any aspect of the modeling process, either with FISH or with Python, both opens up a tremendous amount of power and ends the user’s status as a novice. From the simplest utility to full automation, parameterization, or specialized calculation (or all of the above)—the path to all model- and modeling-process customizations heads in this direction.