Open Source Physics offers the biggest catalog of free Easy Java/Javascript Simulations. The OSP Moodle Repository Plugin lets you download those simulations directly from your Moodle site.
The OSP plugin looks in the descriptions of the simulations stored in Open Source Physics for the conjunction of the terms introduced in the query field.
For instance, if your query is heat, then the plugin will show all the simulations whose descriptions include the word heat. If the query is expanded to heat fluid, then the search will be contrainted to those simulations whose descriptions include both words heat and fluid.
Note that the ordering of the words in a query does not care. So, both queries fluid heat and heat fluid will produce exactly the same outcomes.
For example, the query moon phases js lists all the JavaScript simulations whose descriptions include moon and phases.
As the Open Source Physics just contains Java and JavaScript simulations, the default behavior of a query that does not include java nor js is equivalent to including both words. For instance, moon phases and moon phases js java will produce exactly the same results.