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ramé-hart instrument co.
June 2013 Newsletter
Some of our customers have begun using an
interactive program called Surface Evolver1 which is used to
define and study surfaces that are formed by surface tension and other
energies. The program allows the user to define a surface which can be
saved to a file. The program then evolves the surface toward a minimal
energy surface using a gradient descent method using surface tension,
gravity, and other energies that have been entered into the system.
Other constraints can also be defined.2 The program, written by
Kenneth Brakke at Susquehanna University, is available at no charge.3
We downloaded a copy of the Windows edition of the program and went through some tutorials. It's not a simple program to use. However, the samples files are very helpful, and it's incredibly powerful once you get your information loaded up. We were most interested in contact angle simulation. In the sample shown below, we simulate a sessile drop of liquid on a flat surface. The semispherical top surface which represents the liquid/air interfacial area forms a contact angle with the flat bottom surface (at the liquid/solid interface). In the first sample, the contact angle is about 45°. We changed some parameters and the contact angle increased to about 135° in the second screen. The user can control the parameters used to define the surface as well as the energies that drive the evolution of the surfaces.
Surface Evolver is a very handy and powerful tool for simulating surface behaviors as a function of surface tension and other energies. However, it does not replace the need for physical analysis such as contact angle measurement. In the case of contact angle, there are simply too many parameters - roughness, cleanliness, surface energy, chemical composition, topography, Cassie and Wenzel regimes, etc. - that cannot all be accurately defined in a simulator.
If you already use Surface Evolver or begin using it and find it helpful, please send us a note about your application. We are always interested in learning how our customers are using different tools to solve surface science problems.
|New Product Announcement: Temperature Logger Model 100-32|
Last month we announced a new
Environmental Chamber with a temperature range from -50° to 150° C. This
has been an exciting new product which we are really pleased with. This
month we are releasing another new product - the ramé-hart
Logger (p/n 100-32).
The Temperature Logger uses technology and software that we developed while designing the Peltier Environmental Chamber. The device connects to a thermocouple which collects the temperature data. The thermocouple can connect to an existing ramé-hart Environmental Chamber (100-07) or Advanced Chamber (100-26) or any other chamber. The Temperature Logger connects to the PC via a USB serial connection. With DROPimage Advanced (v2.7 or higher), the temperature can be logged as a function of time using any time-dependant experiment (contact angle or surface tension). The updated reporting engine now also includes a temperature column. The temperature range is -50° C to 750° C using a standard Type J thermocouple. Additional ranges are available on a custom basis using other thermocouple types.
If you have any questions regarding our
Temperature Logger, would like to understand better how it might benefit
your application, or if you would like a quotation for this product,