Computational fluid dynamics simulations in aerosol and nucleation studies

Nucleation is the first step in the formation of a new phase inside a mother phase. Two main forms of nucleation can be distinguished. In homogeneous nucleation, the new phase is formed in a uniform substance. In heterogeneous nucleation, on the other hand, the new phase emerges on a pre-existing surface (nucleation site). Nucleation is the source of about 30% of all atmospheric aerosol which in turn has noticeable health effects and a significant impact on climate. Nucleation can be observed in the atmosphere, studied experimentally in the laboratory and is the subject of ongoing theoretical research. This thesis attempts to be a link between experiment and theory. By comparing simulation results to experimental data, the aim is to (i) better understand the experiments and (ii) determine where the theory needs improvement. Computational fluid dynamics (CFD) tools were used to simulate homogeneous onecomponent nucleation of n-alcohols in argon and helium as carrier gases, homogeneous nucleation in the water-sulfuric acid-system, and heterogeneous nucleation of water vapor on silver particles. In the nucleation of n-alcohols, vapor depletion, carrier gas effect and carrier gas pressure effect were evaluated, with a special focus on the pressure effect whose dependence on vapor and carrier gas properties could be specified. The investigation of nucleation in the water-sulfuric acid-system included a thorough analysis of the experimental setup, determining flow conditions, vapor losses, and nucleation zone. Experimental nucleation rates were compared to various theoretical approaches. We found that none of the considered theoretical descriptions of nucleation captured the role of water in the process at all relative humidities. Heterogeneous nucleation was studied in the activation of silver particles in a TSI 3785 particle counter which uses water as its working fluid. The role of the contact angle was investigated and the influence of incoming particle concentrations and homogeneous nucleation on counting efficiency determined.Hallitustenvälinen ilmastonmuutospaneeli IPCC (Intergovernmental Panel on Climate Change) toteaa vuoden 2007 raportissaan, että aerosolihiukkasten vaikutus ilmastoon on toisaalta mahdollisesti hyvin merkittävä (samaa suuruusluokkaa kuin metaanin tai jopa CO2:n) ja toisaalta myös hyvin huonosti ymmärretty. Jos halutaan kuvata aerosolit ilmastomalleissa oikein eli käytännössä ennustaa luotettavasti ilmaston tulevaisuus, täytyy pienhiukkasten roolia siis pyrkiä ymmärtämään paremmin. On tiedossa, että noin 30 % aerosolihiukkasista muodostuu ilmakehän höyryistä. Tämän prosessin ensimmäistä askelta kutsutaan nukleaatioksi. Sitä havannoidaan luonnossa, sitä tutkitaan kokeellisesti kontrolloiduissa laboratorio-oloissa ja sitä yritetään ymmärtää teoreettisestikin. Teorian ja (laboratorio-)kokeen välimaastoon sijoittuu simulaatio, jonka avulla pyritään (a) mallintamaan jonkin kokeen käyttäytymistä ja (b) parantamaan teoreettista ymmärrystä. Laskennallinen virtausmekaniikka (CFD, Computational Fluid Dynamics) käyttää numeerisia metodeja ja algoritmeja analysoidessaan virtausongelmia, joita on vaikeaa tai mahdotonta ratkaista analyyttisesti. Yleensä ongelman geometria pilkotaan pieniksi soluiksi, joissa sitten ratkaistaan yksinkertaistetut, linearisoidut versiot virtauksia kuvaavista Navier-Stokes-yhtälöistä (finite volume method). Tässä työssä käytetään CFD-koodi Fluentia yhdessä aerosolimalli FPM:n kanssa. Ajatuksena oli antaa kaupallisen CFD-ohjelman hoitaa luotettavasti massan- ja lämmönsiirto, jolloin saatettiin paneutua hiukkasmallin yksityiskohtiin. Tällä asetelmalla on tutkittu niin nukleaation perustavanlaatuisia ilmiöitä (esim. paine-efekti n-alkoholien nukleaatiossa) kuin veden ja rikkihapon nukleaatiota, jolla on keskeinen rooli ilmakehän hiukkasten muodostumisessa. Näiden lisäksi on analysoitu hiukkaslaskuria, jonka toimintametodi perustuu (heterogeeniseen) nukleaatioon

Sola Fide The Relevance of Remembering the Reformation

This two-part publication presents Erik Herrmann’s essay on the ongoing relevance of Martin Luther’s Reformation in light of its 500th anniversary, as well as his sermon on “sola fide” (faith alone), one of the hallmark slogans of the Reformation, which he preached on the 500th anniversary, October 31, 2017

Why Then the Law? Salvation History and the Law in Martin Luther\u27s Interpretation of Galatians 1513-1522

Herrmann, Erik H. \u27Why Then the Law?\u27 Salvation History and the Law in Martin Luther\u27s Interpretation of Galatians 1513-1522. Ph.D. Diss., St. Louis, MO: Concordia Seminary, 2005. 283 pp. This study examines Luther\u27s early exegesis of Galatians 3: 19-4:7 and its relationship to his theological development, especially his doctrine of law and gospel. Luther\u27s earliest exegetical lectures on the Psalms (1513-15) demonstrate essential agreement with the interpretation of Galatians common throughout the exegetical tradition. The law\u27s function is understood solely in terms of its preparatory role in salvation history among Old Testament Israel. It has no value beyond the coming of Christ, who instead imparts the new law of the gospel. Like the Old Testament itself, the law ought to be interpreted spiritually, a type and shadow of the evangelical law. In Luther\u27s lectures on Paul, first Romans (1515-16) and then Galatians (1516-17), a new understanding develops which interprets Paul\u27s doctrine of the law more broadly so that its preparatory role is applicable in all times. Coupled with an increasingly more radical view of sin, Luther comes to interpret Galatians as a description of the law\u27s theological function on the individual conscience, regardless of the dispensation of salvation history. Rather than a veiled type foreshadowing the spiritual doctrines of the gospel, the law prepares one for the gospel by revealing man\u27s sin, a testimony to the fundamental human situation. Important in this transformation are the anti-Pelagian writings of Augustine, which Luther read thoroughly during this time, and his dispute with late scholastic theology and its doctrine of merit. Luther\u27s published commentary on Galatians in 1519 along with the Weihnachtspostille of1522 represent the public presentation of this interpretation of Paul, marking the beginning of Luther\u27s influence on the history of Pauline exegesis. These are especially significant in the context of Luther\u27s relationship to the German reform movement and his escalating conflict with the papacy. A final chapter makes some further observations on the possible consequences that Luther\u27s interpretation of the law had for hermeneutics. Unlike traditional spiritual exegesis which is grounded in the progression of revelation in salvation history, Luther finds the distinction of law and gospel better equipped to address the problem of application. The four-fold method of interpretation is eventually abandoned in favor of this distinction as the primary hermeneutical approach to the Scriptures

Holy Trinity • Acts 2:14a, 22–36 • May 31, 2015

For Peter, gifted now with the Holy Spirit, all that has taken place was promised long ago and has unfolded according to God’s “definite plan and foreknowledge.” In spite of all appearances, the death of Jesus does not negate the “mighty works, wonders and signs” of God

All Saints’ Day • Revelation 7:9–17 • November 2, 2014

Washed and clothed in white robes, God will “shelter them with his presence

Epiphany 2 • Isaiah 49:1–7 • January 19, 2014

This is the great epiphany—the mystery hidden for ages but now revealed, the surprising “new thing” of God’s salvation

Devotion in an Age of Distraction

Dr. Arand explores our connection to creation in our devotional life

Living In the Promises and Place of God- A Theology of The World

This Concordia Pages explores how locating the story of salvation within the broader, biblical story of creation impacts our witness in the world. In particular, it considers how being placed alongside our fellow creatures as recipients of God’s goodness and mercy opens up the possibility for a reciprocity of witness—the way in which our lives, contingent and intertwined, allow for both Christians and non-Christians to bear witness to the work and wonder of God. In such a context, the uniqueness of the Christian witness finds renewed purchase and possibility

Attending to the Beauty of Creation and the New Creation

The beauty of the earth, in all its intricacies, is a gift of the creator to us. And its value is not practical or ethical, but is given to us simply to delight us even as God delights in it. And it is powerful. N. T. Wright notes that beauty, whether in God’s creation or in human art, “is sometimes so powerful that it evokes our very deepest feelings of awe, wonder, gratitude, and reverence.”1 Beauty blossoms into appreciation for God’s creation and love of the creator