AFT Fathom's hydraulic solution engine is based on the Newton-Raphson matrix iteration method plus many proprietary solution methods developed by AFT over several years that increase solution speed and robustness for solving pipe flow and duct flow applications.

Four solution methods are available:

• Constant fluid properties
• Variable fluid properties - user may specify differing fluid properties on a pipe by pipe basis
• Heat transfer with energy balance, single fluid - modeling heat transfer through pipe boundaries and heat exchangers along with fluid property variations with temperature
• Heat transfer with energy balance, multiple fluids - modeling heat transfer between multiple hydraulic circuits thermally linked through heat exchangers

Newtonian and non-Newtonian fluids are supported.

While the following provides an outline of AFT Fathom's capabilities and how it is used, it cannot replace first hand experience so that we invite you to download a free, working demo to try yourself or contact about receiving an evaluation license that will allow you to run the full version for a limited time period.
 

• Reservoir (up to 25 pipes may be connected to each)
• Branch (up to 25 pipes may be connected to each)
• Pump (as fixed specified flow or pump curve and single or multiple configurations)
• Heat exchanger
• Assigned flow
• Assigned pressure
• Area change
• Bend
• Tee/wye (uses the Idelchik and Miller loss relationships)
• Valve
• One way valve (check valves and relief valves)
• Control valve (pressure reducing, pressure sustaining, constant pressure drop, flow - may be specified as fail open or close and fail upon reverse flow)
• Dead end
• Orifice
• Venturi
• Screen
• Spray discharge (single or multiple outlets [sparger])
• Eductor/jet pump
• Volume balance (differing fluids interface)
• General component (user defined component)

An AFT Fathom model is 'assembled' by dragging the junctions to be included onto the Workspace and connecting them with pipes (this can be done in any order and pipes and junctions can be added and deleted at any time). The resulting system schematic clearly displays the connective relationship between system components and pipe runs in the same way traditional schematics and diagrams do.

Each item on the Workspace is described through a Specifications window, opened by double-clicking on the object. In the case of pipes, for example, the diameter, length and roughness are specified (pipes may also be selected by material type and schedule from the built-in database and friction modeling may be selected from an extensive list including, absolute roughness, hydraulically smooth, frictionless and others). In the case of pumps, one selects between a fixed specified flow or modeling with a pump curve. If the latter is selected, data is input for the flow vs. head (or pressure) curve and Fathom calculates a curve fit to characterize the head curve (and, optionally, the NPSHR and efficiency curves). In addition, multiple pump configurations may be specified within a pump junction; e.g. data for a range of impeller diameters and speeds for a particular pump model, as well variable speed pumps and controlled pressure and flow pumps.

A summary of an object's specification may be seen by right-clicking on it to open the Inspection Window.

System lineup can be easily and quickly varied by opening and closing pipes and valves, pumps turned on or off, control valves set to fail position.

AFT Fathom includes numerous tools for arranging and editing models that significantly reduce the time required to develop a model and change it incluiding global editing, powerful selection tools to select objects by a variety of input and output parameters, junction type, named group and more. Drawing tools provide great flexibility in developing your model diagram how you want quickly, including an automated orthogonal pipe drawing mode.

View Workspace Screen Shot
View Pump Specifications Screen Shot
 

The Model Data window provides a tabular listing of the pipes' and junctions' input data. This is a great aid for some types of input review. For example, knowing that your pipe lengths are the range of a few feet to several tens or hundreds of feet, a scan down the pipe length column will quickly reveal an input value with an extra digit or two or a length unit mistakenly specified as miles instead of feet. Double-clicking on an item within the Model Data window opens its Specifications window for editing.
With multiple scenarios Model Data may be configured to display input data for the current scenario and its ancestors clearly illustrating how the scenario differs from higher order scenarios and which parameters are linked and will automatically inherent changes made to higher order scenarios.

View Model Data Screen Shot
 

A tabular display of calculated results, the Output window is organized into General, Pipes and Junctions sections, which can be displayed all at once or individually. Additionally, the General and Junctions sections have tabbed sub-sections to quickly view specific categories. For example, the General section provides tabbed summaries for pumps, valves and heat exchangers, displaying output parameters specific to these types of junctions. The Junctions section has tabs to view the output results of all junctions as well as a tab for each type of junction in the model.

The Output window provides extensive control by the user for such items as; what objects and parameters are displayed, units, order (including sorting), as well format controls for viewing and printing, all of which may be changed and the revised output viewed without re-running the model. Parameters may also be displayed simultaneously with multiple units allowing, for example, to display flow in gal/min and m3/hr side by side.

View Output Screen Shot
 

Working in both Input or Output mode, Visual Report displays selected input or output parameters with your model schematic. Visual Report can vary the color of pipes in the model according to a user defined color map based pressure, temperature, flow and many other parameters.

View Visual Report Screen Shot
 

Graphs of flow, pressure, temperature and many other parameters are quickly and easily generated by pipe or along a flowstream as well as system curves and pump vs. system curves. For multiple pump systems, the various compound pump curves for different combinations of pumps in operation can be shown in one pump vs. system curve providing a clear indication of how system performance will vary with the number of pumps in operation.

View Graph Results Screen Shot
 

A powerful aspect of modeling software is the ability to change the system and study the effects - 'what if'. AFT Fathom's Scenario Manager raises this 'what if' capability to new levels by, first, allowing the user to define variations of a model and save them within one model file and two, automatically keeping common attributes between scenarios synchronized.

Scenarios may vary by almost modeling parameters; pipe sizes, fluids, pump curves, valve settings, indeed, scenarios may differ by the elements present. For example, a variant of a model may have an additional branch or loop than its 'parent'.

Changes in higher order scenarios are automatically passed downward to their 'children' for the parameters that are linked. Consider, for example, having a base scenario with several variants each with different pump curves. To change, say, the size of the pump discharge line on all variants, the Base can is selected, the change made and automatically passed to the 'children', both saving time and ensuring the variants remain synchronized in their common attributes.

View Scenario Manager Screen Shot
 

AFT Fathom provides extensive customization features including:

• Workspace appearance (colors, line widths, fonts, junction sizes and appearance, location of pipe numbers and names, notation).
• Preferred unit specification - English and SI units supported
• Apply design factors to pipe and junction losses, pump head and heat transfer
• Vary pipe thickness (with pipe diameter if desired)
• Fluid, Component, Material and Insulation Databases - AFT Fathom comes standard with a database of ~70 fluids and pipe dimensions and roughness for several types of steel, cast iron and PVC pipe, but you can readily add your own items. Work frequently with copper tubing? Input the data for the sizes you normally work with and they appear in drop down lists along with the standard database items. Fluids can be specified as a single point or with temperature dependent data and AFT Fathom does the work of curve fitting the data to an equation. Specified a pump that you will use again? Click on 'Add Component to Database' and it's readily available from a drop down list. In fact, you can easily compile catalogs of pumps, valves, heat exchangers...virtually any kind of piping component to be quickly and easily selected within AFT Fathom. Better yet, database files can be shared either by copying between stand alone computers or across a network.