Outline

Basics

What is RheoChart?
RheoChart is a charting program to analyse the behaviour of differential viscoelastic models in simple flows. RheoChart can also fit model parameters to experimental data.
Why RheoChart was created?
As part of my PhD thesis at The University of Queensland I did a lot of numerical simulations on differential viscoelastic models and I thought it would be nice to have a program that would facilitate these simulations much easier to do. Also, I love to program so it was all natural to start this project.
When did you start working on RheoChart?
I started back in 2005. But it is only now (in 2009), that I did the extra-mile and added the infrastructure to make this project public.
Where can I find more documentation on RheoChart?
The only source of documentation is currently the web site and the support forum. Check the support page for other options. We will try to improve this, but currently our focus is still on improving the software it-self.
What are the licensing terms?
You can find the license here. Additional, information are also available at this page
How much does RheoChart cost?
Please see the purchase page for pricing information.
Are upgrades free?
Upgrades (minor and major) are free for one year after the date of purchase for the Personal and Professional License. No upgrade is included with the Student License.
Can I use the same license key for RheoChart both at home and at work?
Absolutely. You can use the same license on multiple machines so long as only one copy is being used at a time.
What do I do if I've lost my license key?
mentioning your name and any other useful details such as the purchase date and/or the company name.

Installation

What Microsoft platforms are supported by RheoChart?
RheoChart is being developed on Windows XP. So, we would expect RheoChart to be running on all recent Microsoft Windows platforms - that's Windows XP, Vista and Windows 7. However, if you are using 64-bit Vista or Windows 7, you'll need to use a 32 bit version of the Java Runtime Environment (JRE)
Is there a 64 bit version of RheoChart on Windows?
Not currently, as this would add significant overhead for each release with a minimal benefit. However, if you can't install a 32 bit JRE, please so that we can work on a solution.
Is there a Linux version of RheoChart?
RheoChart has been developed both on Windows XP and Ubuntu 8.04, so a Linux version is not out of reach. However, for the same reason as we don't provide a 64 bit Windows version, a Linux version is not available for download. But again, if you need a Linux version, please
Wait a minute, you just said that Rheochart was a Java program, why can't I run it on Linux then?
The Graphical User Interface (GUI) of RheoChart is indeed developed in Java and as such can run on any platform which support a JRE environment. However, the solver is implemented in C++ and a native library (*.dll on Windows, *.so on Linux) is therefore required to run RheoChart.

Models

Is there any limitations on the number of mode in a model?
No, except with the Demo License which only allows for one mode.
What Generalised Newtonian Models are currently implemented?
  • Power law
  • Bird-Carreau-Yasuda
  • Cross
  • Bingham
  • Herschel-Bulkley
  • Log-Log
What Viscoelastic Models are currently implemented?
  • Double Convected Pom-Pom model (DCPP)
  • Giesekus model
  • Phan-Thien Tanner model (PTT)
  • Upper-Convected Maxwell (UCM)
  • FENE-P
  • White-Metzner

Material functions and properties

Can you do complex flow simulations with RheoChart?
No, RheoChart can only be calculate material functions and properties in simple (shear or elongational) flow.
Where can I find more information about material functions
Most material functions implemented in RheoChart are defined and described in the official nomenclature of The Society of Rheology (SOC) which is available here (SOC)
What is the multi-ramp shear stress property
In a transient shear flow, the shear rate profile is imposed a multi-ramp function. For example, the profile below is defined with 5 points: (0,0), (1,10), (2,10), (3,0) and (4,0). In this case the last point (4,0) is redundant.
The shear rate at time before the first defined point is taken equal to the shear rate of the first point (in this case 0). Similarly, the shear rate at a time after the last point is equal to the shear rate of the last point.
In case of doubt, it is easy to check the function, by using a Constant viscosity mode with a viscosity of 1. The stress profile will be equal to the shear rate profile.
Can I calculate the shear stress relaxation in a step strain?
It is not possible to calculate a pure step strain as this would involves an infinite shear rate, but it is possible to simulate something reasonably close by using the multi-ramp shear stress. For example, to calculate the decay in stress after a step strain of 10, a multi-ramp shear stress function with 3 points can be used: (0,0), (1.0E-04, 1.0E+05) and (2.0E-04, 0). This would ensure that a total strain of 10. Obviously the points of the multi-ramp function needs to be selected so that the total strain is achieved in a time much smaller than the relaxation time of the material.
What is the multi-ramp shear rate property
This property is very similar to the "multi-ramp shear stress property" where the shear stress profile is imposed rather than the shear rate. The calculated property is the shear rate that is observed under that stress condition.
Note that for this property, the initial state of the stresses should equals to zero. In other words, the shear stress at the first point should always be 0.
Can I calculate the shear creep rate decay function?
This is a similar problem as for the shear stress relaxation. It can be calculated exactly, but a good approximation can be obtained by using the multi-ramp shear rate property.

Fitting

How many modes/properties can be used in a fitting?
As many as you want, however it's probably a good idea to only adopt the following approach:
  • Select a range of relaxation times and fix the relaxation times
  • Fit the linear parameters using the storage and loss moduli, leaving the non-linear parameters constant.
  • Fit the other-parameters, leaving the linear parameters constant.
What's the initial value of a parameter in a fitting?
The initial value is the value of the parameter defined in the "Parameters" tab.
How can I import experimental data in RheoChart
To import experimental data into RheoChart, you need to use the tab Curve, then select experimental and you'll find a button Import. You can have a look at the screencast which demonstrates this feature.
File that can be imported are simple text file. RheoChart will attempt to read 2 different formats before giving up:
  • A simple 2 columns format, where columns are separated by white spaces. Any line starting with a # is ignored (so first column is X and second column is Y)
  • CSV format, in which the first column is the row number, then X and then Y
The easiest to check the format is to export a curve from RheoChart and look inside the file with a text editor.
Can I applied some constraints on a parameter in a fitting?
Yes, this is done in the "Fitting" tab visible when a mode is selected. A parameter can be constant (i.e. not used in the fitting), vary freely (no constraint) or constrained (lower and/or upper limit can be applied).
After a fitting, I would like to keep the initial values of all the parameters?
Simply, select the option "Restore original values" in the dialog launching the fitting. Note, that you'll lose the solution found during the optimisation process.