Ferrofluid Piston

A good application for ferrofluid is to seal the cylinder of a Stirling motor. The piston shall seal the cylinder and it shall run with low friction. Achieving both targets requires some precision It becomes simple when thin magnetic oil, stays attached to a magnetic piston. Forming an elastic sphere around the magnet, the oil closes the gap. The piston is even centered in the cylinder. For demonstration the working cylinder is extended with a displacement cylinder to a Stirling motor. For the operat