]><link href="/styles/xml_display.css" rel="stylesheet" type="text/css" /><link href="/styles/xml_tables.css" rel="stylesheet" type="text/css" /><link href="/styles/tables_alg.css" rel="stylesheet" type="text/css" /></head><body style="background: white"><table class="table-group" width="800px"><tr class="fig-image" id="a"><td><img alt="782457.fig.002a" src="../../782457.fig.002a.jpg"/></td></tr><tr class="fig-caption"><td align="center"><table><tr><td><b>(a) </b></td></tr></table></td></tr><tr class="fig-image" id="b"><td><img alt="782457.fig.002b" src="../../782457.fig.002b.jpg"/></td></tr><tr class="fig-caption"><td align="center"><table><tr><td><b>(b) </b></td></tr></table></td></tr><tr class="fig-group-caption"><td><table><tr><td><b>Figure 2: </b>Variations of (a) damping <math id="M55" xmlns="http://www.w3.org/1998/Math/MathML"><mo stretchy="false" >(</mo><mtext >Real</mtext><mo stretchy="false" >(</mo><msub ><mrow><mi>λ</mi></mrow><mrow><mi>j</mi></mrow></msub><mo stretchy="false" >)</mo><mo stretchy="false" >)</mo></math> and (b) frequencies <math id="M56" xmlns="http://www.w3.org/1998/Math/MathML"><mo stretchy="false" >(</mo><mtext >Imag</mtext><mo stretchy="false" >(</mo><msub ><mrow><mi>λ</mi></mrow><mrow><mi>j</mi></mrow></msub><mo stretchy="false" >)</mo><mo stretchy="false" >)</mo></math> with the freestream velocity <math id="M57" xmlns="http://www.w3.org/1998/Math/MathML"><mrow ><mi>U</mi></mrow></math>.</td></tr></table></td></tr></table></body></html>