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With the planning of new ambitious gravitational wave (GW) observatories, fully controlled laboratory experiments on dynamic gravitation become more and more important. Such experiments can provide new insights in potential dynamic effects such as gravitational shielding or energy flow and might contribute to bringing light into the mystery still surrounding gravity. Here we present a laboratory-based transmitter-detector experiment using two rotating bars as transmitter and a 42 Hz, high-Q bending beam resonator as detector. Using a highly precise phase control to synchronize the rotating bars, a dynamic gravitational field emerges that excites the bending motion with amplitudes up to 100 nm/s or 370 pm, which is a factor of 500 above the thermal noise. The two-transmitter design enables the investigation of different setup configurations. The detector movement is measured optically, using three commercial interferometers. Acoustical, mechanical, and electrical isolation, a temperature-stable environment, and lock-in detection are central elements of the setup. The moving load response of the detector is numerically calculated based on Newton’s law of gravitation via discrete volume integration, showing excellent agreement between measurement and theory both in amplitude and phase. The near field gravitational energy transfer is 1025 times higher than what is expected from GW analysis.

In this article, we present the Open-Source AcoustoFluidics Theories (OSAFT) library (version 0.9.14), a Python library for acoustofluidics. The focus of the library is the classical problem of a particle suspended in a fluid and subjected to an incident acoustic wave. The Python code provides easy access to a number of theories describing acoustic scattering, acoustic streaming, and most importantly the acoustic radiation force exerted on the particle. At the time of submission of this article, six different theoretical models and various limiting cases thereof are available. All are treating the problem of a single, spherical particle in an infinite 3D-domain subjected to an incident plane standing or plane traveling wave. The implementations of further theories are currently under development. Our code is designed to be extensible. A library of fluid and solid material models facilitates the implementation of new theories. A unified application programming interface (API), which is used across all models, makes comparisons between different theories straightforward. Such comparisons can be made directly by the user or through the plotting capabilities of our library. The code is distributed through Python’s standard software repository PyPi. Illustrative examples on the project’s website serve as a starting point for learning the library’s API. For a more in-depth understanding of the code, complete documentation of the codebase, directed at users as well as future collaborators, is available online. In an effort to make the library as extensive as possible, the authors of this article are looking for collaborators on the project.