As both .ova and .vmdk files are disk images for virtual machines, ova to vmdk conversion should be no problem. You just need to use virtual machine software that supports both formats.
Generally, VirtualBox can export its default virtual machine format to several other formats, including .vmdk files from VMWare. The same goes for VMware, which supports VirtualBox formats just fine, so you may also use this program to convert ova to vmdk.
Updated: April 19, 2024