The physical aspect of auditions, to me, has three main sides to it: performance, energy, and neutral state. In the days leading up to the audition, it's really important to take care of yourself. Enough nutrition and water to avoid any sickness and dehydration, and enough rest to avoid exhaustion and burnout. This is your "neutral" state, where you are in the holding area or musician's lounge waiting to play. Know what foods will be good for that day, it's different for everyone. Maybe coffee makes you jittery, so don't drink it well before that day comes, allowing it to completely leave your system. Every chance you have to make sure your body is ready to work, take it, go all out with it. You want to be thinking about the music, not, "Man, I'm really hungry/tired."
Next is the energy state, where "nerves" come into play. In my opinion nerves are just extra energy for your body to complete a difficult task, in our case, performing in front of a panel, any audience really. The trouble with this state is that it's hard to practice navigating these energies outside of the actual audition. Many have recommended running up and down a flight if stairs, or doing jumping jacks to simulate that feeling, but, at least for me, it doesn't feel the same. However, if you create a situation where you have to perform in front of a panel, that will give rise to the energy. So, getting in front of people, putting yourself on the spot and playing for as many audiences as you can will help you get to know that feeling, so that, when they do come up, it's not new to you, but common, even welcome. Nerves will help you play better, not worse.
Finally, the performance, my favorite part. As you are preparing for the audition, you will become more accustomed to the physical endurance and activity that will be required during rounds, and it's important to really learn and practice that. In my case, how does one go from playing a loud excerpt to a soft one? What if they ask you to replay a snare excerpt after you've played a cymbal excerpt? Playing different combinations of lists will help simulate different circumstances you may be faced with during a round, and gives you more flexibility within the entire audition. Try longer lists, or go from loud sustained excerpts to soft articulate ones. The more combinations you can try, the less surprised you'll be with whatever they put in front of you. When you do go to play, it should feel as close as possible to how you practiced. Yes, you have to adjust to the hall, but rather over or under working, just adjust whatever feel you've worked on to that difference.
I've tried a lot of things when it comes to preparing the body for an audition, and it really comes down to what will make you as comfortable as possible in a "stressful" situation. Take note anything that happens whenever you get nervous, not just when you perform. Do your hands shake, does your breathing thin out or get faster? Even ask yourself what you'd prefer during the moments before the audition. Do you like to eat in the morning or do you feel better if you haven't eaten (I like eating way before, giving me a chance to digest, but not feel hungry or full). Answer as many questions as you can pose and when the day comes you won't be as surprised if something does come up. If you take those proper steps to take care of yourself and plan for the physical demands, and issues that come with nerves, you will have a better handle on any performance. Happy practicing!