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    <p>Loïc,</p>
    <p> Sorry for misinterpreting your question. I think you do need to
      delete the adjacent surfaces and get one large radiation zone that
      includes your stack of airnodes. Then you use the "coupling
      between airnodes" popup to define the rate at which air moves from
      one of the air nodes to the other.</p>
    <p> If you drew your building in SketchUp you can draw in the
      adjacent surfaces between the airnodes and assign them as the
      "virtual surface" category option (sorry I can't check the exact
      language of the option; my SketchUp install is giving me problems
      right now and I can't launch it to check). In any case if those
      "adjacent" surfaces are set as virtual then they won't be brought
      into the TRNBuild model and thus you won't have to delete them
      manually but will still have the integrity of the airnodes.</p>
    <p>kind regards,</p>
    <p> David</p>
    <p><br>
    </p>
    <div class="moz-cite-prefix">On 1/13/2023 11:27 AM, Loic Tachon
      wrote:<br>
    </div>
    <blockquote type="cite"
cite="mid:CAJ2U-g8BkCPwj74Og_Jy-KicXr1c+BsHcqantNGUwarv9TwBRw@mail.gmail.com">
      <meta http-equiv="content-type" content="text/html; charset=UTF-8">
      <div dir="ltr">
        <div dir="ltr">Thanks for the answer, in my case I know the
          ventilation cross flow induced by the stack effect and I
          suppose that this flow cross all the zone. </div>
        <div dir="ltr"><br>
        </div>
        <div dir="ltr">Do I need to delete the horizontal air nodes
          adjacent surface (surface inside the radiation zone) to get
          just one radiation zone ?   </div>
        <div dir="ltr"><br>
        </div>
        <div>If we know the flow between airnodes, is it better to put
          it via coupling between zones pop up ? <br>
          <img src="cid:part1.sdsBQQuL.Zl0STdcA@tess-inc.com"
            alt="image.png" class="" width="542" height="320"><br>
           or through surface definition, adjacent coupling air flow (if
          the adjacent surfaces are not deleted) ? </div>
        <div><br>
        </div>
        <div><img src="cid:part2.f0Pb21eT.gjWKT0kw@tess-inc.com"
            alt="image.png" class="" width="496" height="129"><br>
        </div>
        <div><br>
        </div>
        <div>Thanks a lot.</div>
        <div><br>
        </div>
        <div>Regards,</div>
        <br>
        <div class="gmail_quote">
          <div dir="ltr" class="gmail_attr">Le ven. 13 janv. 2023
            à 16:56, David BRADLEY <<a
              href="mailto:d.bradley@tess-inc.com"
              moz-do-not-send="true" class="moz-txt-link-freetext">d.bradley@tess-inc.com</a>>
            a écrit :<br>
          </div>
          <blockquote class="gmail_quote" style="margin:0px 0px 0px
            0.8ex;border-left:1px solid
            rgb(204,204,204);padding-left:1ex">
            <div bgcolor="#FFFFFF">
              <p>Loïc,</p>
              <p>  The best way to address airflow within a building is
                to couple your Type56 simulation either with TRNFlow or
                CONTAM (Type97). The basic idea is that you build a
                parallel model to your Type56 containing information
                about the airflow openings between the airnodes (a
                radiation zone can contain multiple airnodes, especially
                where there is an atrium like you have described).
                TRNFlow or CONTAM then take the air node temperatures as
                well as the wind speed and geometry of the building and
                determine the amount of air flow that results between
                the air nodes. Large horizontal openings are challenging
                because both TRNFlow and CONTAM treat air flow through a
                horizontal opening as unidirectional. Still, it is by
                far the most rigorous way of treating the situation.</p>
              <p>kind regards,</p>
              <p> David</p>
              <p><br>
              </p>
              <div>On 1/13/2023 8:29 AM, Loic Tachon via TRNSYS-users
                wrote:<br>
              </div>
              <blockquote type="cite">
                <div dir="ltr">Dear Trnsys community,
                  <div><br>
                  </div>
                  <div>I want to simulate the stack effect in a high
                    room with high thermal gain.</div>
                  <div><br>
                  </div>
                  <div>For this, I have 1 zone and 5 thermal air nodes
                    in the z direction to get the temperature at several
                    heights.  <br clear="all">
                    <div><img
                        src="cid:part3.uCLLFbRB.AA0kP5Dt@tess-inc.com"
                        alt="image.png" class="" width="243"
                        height="480"><br>
                    </div>
                    <div>How can I do this and avoid that TRNSYS see
                      ceiling between the zone ? Do I need to delete the
                      horizontal surface for zone 2-3-4 ? Or do I put
                      mass less horizontal surface ?</div>
                    <div><br>
                    </div>
                    <div>As Well, how do I do the cross flow ventilation
                      ? Do I use the couple mass flow between zones ?</div>
                    <div><img
                        src="cid:part4.cqfpLYCL.9sdxbV3e@tess-inc.com"
                        alt="image.png" class="" width="542"
                        height="323"><br>
                    </div>
                    <div><br>
                    </div>
                    <div> or I put a coupling air flow (same that
                      natural ventilation mass flow) for the horizontal
                      surface ?</div>
                    <div><img
                        src="cid:part5.vaGeHG03.C1R3cI5H@tess-inc.com"
                        alt="image.png" class="" width="503"
                        height="137"><br>
                    </div>
                    <div><br>
                    </div>
                    <div>Thanks a lot. </div>
                    <div><br>
                    </div>
                    <div>Best regards,</div>
                    <div><br>
                    </div>
                    -- <br>
                    <div dir="ltr">
                      <div dir="ltr"><font style="font-size:12.8px"
                          color="#000000"><b>Dr. Loïc Tachon </b></font>
                        <div style="font-size:12.8px">
                          <div><font color="#000000">(+33) 6 7440-0536
                              (France)</font></div>
                          <div><br>
                          </div>
                        </div>
                        <div><font color="#e69138"><b><br>
                            </b></font></div>
                      </div>
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                  </div>
                </div>
                <br>
                <fieldset></fieldset>
                <pre>_______________________________________________
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</pre>
              </blockquote>
              <pre cols="72">-- 
***************************
David BRADLEY
Principal
Thermal Energy System Specialists, LLC
3 North Pinckney Street - suite 202
Madison, WI  53703 USA

P:+1.608.274.2577
<a href="mailto:d.bradley@tess-inc.com" target="_blank" moz-do-not-send="true" class="moz-txt-link-freetext">d.bradley@tess-inc.com</a>

<a href="http://www.tess-inc.com" target="_blank" moz-do-not-send="true" class="moz-txt-link-freetext">http://www.tess-inc.com</a>
<a href="http://www.trnsys.com" target="_blank" moz-do-not-send="true" class="moz-txt-link-freetext">http://www.trnsys.com</a></pre>
            </div>
          </blockquote>
        </div>
        <br clear="all">
        <div><br>
        </div>
        -- <br>
        <div dir="ltr" class="gmail_signature">
          <div dir="ltr"><font style="font-size:12.8px" color="#000000"><b>Dr.
                Loïc Tachon </b></font>
            <div style="font-size:12.8px">
              <div><font color="#000000">(+33) 6 7440-0536 (France)</font></div>
              <div><br>
              </div>
            </div>
            <div><font color="#e69138"><b><br>
                </b></font></div>
          </div>
        </div>
      </div>
    </blockquote>
    <pre class="moz-signature" cols="72">-- 
***************************
David BRADLEY
Principal
Thermal Energy System Specialists, LLC
3 North Pinckney Street - suite 202
Madison, WI  53703 USA

P:+1.608.274.2577
<a class="moz-txt-link-abbreviated" href="mailto:d.bradley@tess-inc.com">d.bradley@tess-inc.com</a>

<a class="moz-txt-link-freetext" href="http://www.tess-inc.com">http://www.tess-inc.com</a>
<a class="moz-txt-link-freetext" href="http://www.trnsys.com">http://www.trnsys.com</a></pre>
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