e></head><body><div class = "content"><div class = 'SectionBlock containment active'><div class = "S1"><span class = "S2"><span class="S0">The eigenvalues of advection--diffusion are near-imaginary for</span></span><span class = "S2"><span class="S0"> </span></span><span style="vertical-align:-5px"><img src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAEgAAAAkCAYAAAAq23xmAAAElklEQVRoQ+2YachuUxTHf1emSxkypRQZMg91M0RJ+EBmkXmM7jVPGTNFpi/I9IHMZLyu634hcygkU4mMiSKKMkTmfre13/a7n3POPo/XB/e9Z9Xb87zPHs7a//1f/7XWmcFg