<p><span style=”font-size: 12pt;”>Hello everyone,<\/span><\/p><p><span style=”font-size: 12pt;”>I am trying to determine the time required for a 50-liter tank, initially at atmospheric pressure, to reach its nominal pressure of <span class=”katex”><span class=”katex-mathml”>11⋅10^5 P<\/span><span class=”katex-html” aria-hidden=”true”><span class=”base”><span class=”mord”>a<\/span><\/span><\/span><\/span>, knowing that it is pressurized by a compressor supplying air at <span class=”katex”><span class=”katex-mathml”>12.5⋅10^5 Pa <\/span><\/span>through a circular inlet with a diameter of 12 mm.<\/span><\/p><p><span style=”font-size: 12pt;”>I attempted to model this problem in Fluent, but the results I obtained are not satisfactory: the pressure evolution in the tank shows a linear behavior over time until it stabilizes at <span class=”katex-mathml”>12.5⋅10^5 Pa<\/span>; the airflow rate at the inlet remains constant and then drops to zero once pressure equilibrium is reached. This result is physically inconsistent.<\/span><\/p><p><span style=”font-size: 12pt;”>I expected to observe a significant increase in pressure during the initial moments, followed by a progressive decrease in the slope of the pressure evolution until reaching an asymptote at pressure equilibrium. Similarly, the airflow rate should decrease over time in the same way.<\/span><\/p><p><span style=”font-size: 12pt;”>Model setup:<\/span><\/p><\/p>\n
<li style=”font-size: 12pt;”><span style=”font-size: 12pt;”>Models: Energy (On) \/ SST k-omega<\/span><\/li>\n
<li style=”font-size: 12pt;”><span style=”font-size: 12pt;”>Material: Air (ideal gas for density; other properties are constant)<\/span><\/li>\n
<li style=”font-size: 12pt;”><span style=”font-size: 12pt;”>Operating Pressure : 10^5 Pa<\/span><\/li>\n
<li style=”font-size: 12pt;”><span style=”font-size: 12pt;”>Inlet: Pressure-inlet (Gauge Total Pressure: <span class=”katex-mathml”>11.5⋅10^5<\/span> Pa)<\/span><\/li>\n
<li style=”font-size: 12pt;”><span style=”font-size: 12pt;”>Wall: No slip \/ Adiabatic<\/span><\/li>\n
<li style=”font-size: 12pt;”><span style=”font-size: 12pt;”>Methods: Coupled \/ Distance-based \/ Least Squares Cell-Based \/ All second-order<\/span><\/li>\n
<li style=”font-size: 12pt;”><span style=”font-size: 12pt;”>Time step: <span class=”katex”><span class=”katex-mathml”>5⋅10^<\/span><span class=”katex-html” aria-hidden=”true”><span class=”base”><span class=”mord”><span class=”mord mtight”>−3 s<\/span><\/span><\/span><\/span><\/span><\/span><\/li>\n<\/ul>\n
<p><span style=”font-size: 12pt;”>I considered using the density-based solver since the flow is highly compressible, but it requires a very small time step (<span class=”katex”><span class=”katex-mathml”>1⋅10^−6 s<\/span><\/span>), while the simulation time spans several tens or even hundreds of seconds.<\/span><\/p><p><span style=”font-size: 12pt;”>Do you have any solutions or ideas to correct the physical behavior of the results?<\/span><\/p><p><span style=”font-size: 12pt;”>Thank you in advance for your responses.<\/span><\/p><p><span style=”font-size: 12pt;”>Best regards,<\/span><br><span style=”font-size: 12pt;”>Gaétan<\/span><\/p><\/p>\n","protected":false},"template":"","class_list":["post-395800","topic","type-topic","status-publish","hentry","topic-tag-compressible-flow","topic-tag-density-based-1","topic-tag-fluent","topic-tag-pressure-based","topic-tag-tank-1"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t