v1.8

1. Non-Newtonian liquids: APECSS can now simulate power-law liquids.
2. Examples: Ultrasound example with a power-law liquid has been added.
3. Documentation: Updates and corrections.

v1.7

1. A new APECSS structure, APECSS_Interaction, to gather data needed for the computations of bubble-bubble interactions in multi-bubble systems. This includes a new file interactions.c in the source folder to compute interactions between bubbles considering incompressible interactions (frequently used in the literature) and a new model based on the quasi-acoustic assumption.
2. An update to the binaryinteraction test case, which now incorporates the newly developed structure and function to compute the incompressible interactions between the two bubbles.
3. A new test case, cavitationonset, based on Ida, M. (2009). Multibubble cavitation inception. Physics of Fluids, 21(11), 113302..
4. A new test case, sphericalclustertensionwave, of a monodisperse spherical shape cluster of 250 microbubbles. This includes also an example of how such multi-bubble simulations can be parallelized in a simple manner using MPI.
5. Updates to the documentation.

v1.6

1. Acoustic emissions: The linked list carrying the emission nodes can now be pruned based on a user-defined function.
2. Kirkwood-Bethe hypothesis: Changes to how the computation and update of the invariant f are implemented, to make the explicit velocity expression compatible with the recently introduced shock treatment method.
3. Examples: Corrected reference solution for the spherical acoustic emitter example.
4. Documentation: Updates and corrections.

v1.5

1. Improved treatment for shock waves.

• The multivalued solutions associated with shock fronts are no longer treated by discarding the information of the overtaking emission node in the Lagrangian wave tracking, but by a new averaging procedure that yields better mass conservation.

2. Introduced support for non-spherical bubbles and gas cavities.

• All models based on the Kirkwood-Bethe hypothesis now support arbitrary (quasi) one-dimensional domains, including the bubble dynamics (Gilmore models) and acoustic emissions (KB emissions). Readily available are a planar one-dimensional domain, cylindrical symmetry and, of course, spherical symmetry. See also the new test cases that use this functionality.

3. Removed the spatial integration of the velocity (SIV) for emissions based on the Kirkwood-Bethe hypothesis.

• This method integrated the velocity with respect to the radial coordinate along the outgoing characteristic. However, since it is equivalent to the available temporal integration method (TIV), it has been discontinued in the interest of code clarity.

4. Introduced new examples.

• Planar acoustic emitter.
• Spherical acoustic emitter.
• Rayleigh collapse of a cylindrical bubble.
• Rayleigh collapse that produces a shock wave (including Navier-Stokes reference results).

5. Updates and corrections to the documentation.

6. Minor bug fixes (e.g. in results functions and for simulations using long doubles).

v1.4

This release includes improvements made as a results of the JOSS paper review:

1. Revised Quick Start Guide
2. Improved and corrected documentation
3. Improved in-code documentation of important functionality
4. Added scripts to plot the results of the examples and to run all examples automatically.

v1.3

1. New example (binaryinteraction) simulating the acoustic interaction of two bubbles.
2. Streamlined implementation of the acoustic emissions.
3. Revised formulation of the finite-speed incompressible model for the acoustic emissions.
4. Include the pressure at infinity in the results of the Rayleigh-Plesset model.
5. Automated tests of the basic functionality of the code using Github workflows, testing if the library compiles and if the examples can be run without errors.
6. Updates and corrections in the documentation with respect to points 2, 3 and 5.

v1.2

1. Added a void pointer void *user_data to the structures APECSS_Bubble, APECSS_EmissionNode, APECSS_Gas, APECSS_Liquid and APECSS_Interface. The void pointers allow to easily associate additional data to these structures. The examples laserinducedcavitation and gastemperature provide practical examples of how to use these void pointers.
2. Revised the examples laserinducedcavitation and gastemperature to use the new void pointers.
3. Changed the terminology of the methods to compute the acoustic emissions based on the Kirkwood-Bethe hypothesis, such that the terminology better reflects the differences between the methods.
4. Bug fix for the Keller-Miksis model.
5. Updated the documentation with respect to points 1, 3 and 4, and added short description on how to compile APECSS with debug flags.

v1.1

1. Improvements to the computation of acoustic emissions:

• Established methods of Gilmore and Hickling & Plesset have been included, in which the velocity is integrated along the outgoing characteristic.
• Integration of the radial position and, if applicable, flow velocity using either an Euler or (by default) a fourth-order Runge-Kutta scheme.
• Restructuring and simplification of the "emissions_advance" functions for methods based on the Kirkwood-Bethe hypothesis.

2. New example on laser-induced cavitation, based on the recent work of Liang at al. (JFM 940, 2022, A5).

3. Changes to the documentation:

• Amended the Emissions section incorporating the additional methods.
• Small corrections throughout.

v1.0

Initial release of APECSS.