Frequently Asked Questions

This section of the documentation is intended to provide quick support by answering questions that are frequently asked by users. For information on how to perform simulations, please check out the tutorials.

The FAQ is divided into the following categories:

General

What is a Lumped-Parameter Model?

A Lumped-Parameter Model simplifies a system by lumping the spatial variables into one value for a control volume. As an example, the pressure in a control volume only varies with time and not with location. This is a model order reduction technique in order to reduce computational complexity, and has been proven to be accurate for hydraulic machines.

What operating systems are supported?

  • Windows 10-11

What are the hardware requirements?

The following requirements are recommended:

  • 6 core CPU

  • 16 GB of RAM

Is there a Linux based alternative to Multics without using Docker?

There is no Linux based alternative yet.

Where can I get a Multics license key?

The multics key is provided by a Maha faculty.

Modeling

What units can be used in the inputDict?

Here is a list of acceptable units.

What can be simulated with Multics?

Multics can be used to simulate hydraulic machines, lubricating surfaces, and other dynamic systems.

Multics is primarily used to simulate hydraulic machines, and templates for following hydraulic machines are included with the software.

  • Axial Piston Machine

  • Internal Gear Machine

  • External Gear Machine

  • Gerotor

  • Vane Machine

  • Radial Piston Machine

What numerical integration techniques are implemented in Multics?

The following integrators have been implemented:

  • LSODA - Recommended

  • Runge Kutta - Order (12), (23), and (45)

  • Predictor-Corrector integrator

How do I run multiples cases in batch mode?

The current version of Multics has no a built-in function for running a simulation in batch mode. To evaluate the effect of a specific parameter on the model implemented, the user can change the parameter in the inputDict.txt and run the model. There is no need to recompile the model for every change in the inputDict.txt file.

  • Make sure to do not have any error messages

  • Visualize your simulation results in ParaView

  • Analyze simulation results with the provided 1D plotter

Troubleshooting

What should I do if my simulation is not converging?

If your simulation does not converge, you may want to try the following:

  • Check your input parameters, and make sure the values and units are correct

  • Check the boundary conditions

  • Reducing the time step

  • Changing the solver, or the solver settings

  • Lower the convergence tolerance

What should I do if my simulation is throwing errors?

Attempt the suggestions described on this FAQ page. If that fails, contact us with the errors that you are experiencing.