Print WordPress menu by Targeting a specific menu name
wp_nav_menu( array( 'menu' => 'Project nav' ));
Print WordPress menu by theme location.
If you are using theme location you must be registered with register_nav_menu() in your function.php file.
wp_nav_menu( array( 'theme_location' => 'primary' ));
Checkout for more info about wp_nav_menu().