When you go to the Main Tab, you can now use the VDB files if you change the Type to "VDB Loader". A typical VDB file has properties such as Density, Temperature, and Velocity. You can see them when you load the VDB file. There are free VDB resources on the web but if you want to create your own, you can try Houdini or other simulation softwares, as long as the VDB export is available.
From here you can load the VDB file. You can also see the VDB's info right in the lower box. For example, the VDB file you see in the picture below is taken from OpenVDB.org and the volume medium settings are created according to this VDB info. There are 3 properties (Density, Temperature and Velocity) that are used in this VDB and their channel infos are automatically displayed in the info section.
This option is to see the VDB in viewport. Sometimes you may want to create the scenes with interaction of VDB and other objects. In this case, this option works quite well. With the "Voxel Display" option you can switch the display of the VDB on and off. When you work with a heavy VDB you can turn it off if there is a slowdown in your viewport. With "Density Multiplier" you can increase and decrease the density of voxel in your viewport. The default option 1 is ideal for most scenes.
anImated vdb settIngs
Animated VDBs are very simple to use. Select any VDB from the folder where your VDB sequence is. Then type the start and end frames of the VDB animation in the "Start" and "End" fields. Finally, enter the number of frame digits in the Digits field. That's it. The Loop option does exactly what you expect. However, when running in the source file you may need to prepare the VDB in accordance with the loop.
GRID MAPPING SETTINGS
From here you can get very different looks using the properties of the VDB you have loaded. It normally works in cooperation with Volume Medium. You can set the appropriate feature for each channel from the drop down menu. These features are the features that you have cached in the source software. For example, let's say you produced fire in Houdini, normally the following features are cached in the simulation: Temperature, Density, Velocity. If you want a more advanced fire simulation (like burn) you can include them in sim Cache and export output of vdb. You can then choose from a variety of absorption, scatter and emission mapping features to achieve a wide variety of views. Of course, you can not just make adjustments here, as we said, you should play with a lot of settings from the volume medium tab too. The Scale fields next to the channel names are used to determine how much of your selected feature will affect the Voxel Grid Map. For example, in the following picture, the absorption / density scale value 20 is entered to the explosion VDB (on the right side). Thus the effect of black smoke spread throughout the voxel grid and increased its effectiveness.
velocIty mOTION BLUR
From here you can give motion blur to your VDB. For this option to work, the source VDB must have the velocity property. For example, if you are going to produce fire in Houdini, you need to add the velocity while caching. You can then define the Velocity Vel.x, Vel.y and Vel.z mapping channels and increase the motion blur effect from the scale. Do not forget to activate camera motion blur. You can increase the "Time sampling per frames" setting from the render settings to more accurate motion blur.