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Advection

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1204:, and this correspondence of terms is used in the literature. More technically, convection applies to the movement of a fluid (often due to density gradients created by thermal gradients), whereas advection is the movement of some material by the velocity of the fluid. Thus, although it might seem confusing, it is technically correct to think of momentum being advected by the velocity field in the Navier-Stokes equations, although the resulting motion would be considered to be convection. Because of the specific use of the term convection to indicate transport in association with thermal gradients, it is probably safer to use the term advection if one is uncertain about which terminology best describes their particular system. 1187: 25: 923: 282:
One easily visualized example of advection is the transport of ink dumped into a river. As the river flows, ink will move downstream in a "pulse" via advection, as the water's movement itself transports the ink. If added to a lake without significant bulk water flow, the ink would simply disperse
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of a substance or quantity by bulk motion of a fluid. The properties of that substance are carried with it. Generally the majority of the advected substance is also a fluid. The properties that are carried with the advected substance are
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showing its distribution over space. Advection requires currents in the fluid, and so cannot happen in rigid solids. It does not include transport of substances by
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manner, which is not advection. Note that as it moves downstream, the "pulse" of ink will also spread via diffusion. The sum of these processes is called
946: 1057: 1430: 1228:, humidity or salinity, and convection generally refers to vertical transport (vertical advection). Advection is important for the formation of 666: 1277: 954: 563: 256: 1423: 1178:, this form reduces the "blow up" and "spectral blocking" often experienced in numerical solutions with sharp discontinuities. 723: 1047:{\displaystyle {\tfrac {1}{2}}{\mathbf {u} }\cdot \nabla {\mathbf {u} }+{\tfrac {1}{2}}\nabla ({\mathbf {u} }{\mathbf {u} }),} 1572: 1399: 1884: 185:
During advection, a fluid transports some conserved quantity or material via bulk motion. The fluid's motion is described
89: 856:{\displaystyle {\frac {\partial {\mathbf {a} }}{\partial t}}+\left({\mathbf {u} }\cdot \nabla \right){\mathbf {a} }=0.} 175: 434: 61: 1592: 1416: 1372: 108: 1740: 1879: 68: 1787: 46: 1874: 1619: 1587: 1534: 1904: 1262: 1245: 350: 75: 1848: 1782: 1539: 42: 57: 1762: 1696: 1524: 421:{\displaystyle {\frac {\partial \psi }{\partial t}}+\nabla \cdot \left(\psi {\mathbf {u} }\right)=0,} 305: 1869: 1629: 1481: 868: 764: 732: 533: 1830: 1752: 35: 1899: 1684: 1644: 1597: 1582: 1564: 143: 1889: 1731: 1624: 1614: 1577: 1217: 961: 505: 216: 1810: 1777: 1679: 1674: 1639: 1220:, advection often refers to the horizontal transport of some property of the atmosphere or 897: 705: 8: 1894: 1772: 1757: 1267: 950: 527: 198: 1544: 1287: 1244:
The advection equation also applies if the quantity being advected is represented by a
1233: 1232:(terrain-forced convection) and the precipitation of water from clouds, as part of the 654:{\displaystyle {\frac {\partial \psi }{\partial t}}+{\mathbf {u} }\cdot \nabla \psi =0} 272: 240: 82: 1825: 1721: 1609: 1451: 1395: 1368: 1408: 1387: 1272: 1229: 1172: 268: 1292: 1476: 219:, advection often refers to the transport of some property of the atmosphere or 1767: 1282: 759: 752: 264: 162:
by bulk water flow downstream. Another commonly advected quantity is energy or
1359: 1863: 1549: 1391: 499: 276: 130: 1186: 166:. Here the fluid may be any material that contains thermal energy, such as 1726: 1701: 1634: 1511: 892: 888: 429: 300: 260: 208:, which is the combination of advective transport and diffusive transport. 194: 190: 1815: 1654: 1554: 1213: 1175: 228: 212: 186: 126: 1820: 1792: 1706: 1501: 1486: 1466: 1200: 1190:
The four fundamental modes of heat transfer illustrated with a campfire
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Advection is sometimes confused with the more encompassing process of
1662: 1491: 1471: 1297: 1249: 953:"shock" solutions and necessary conditions for convergence (e.g. the 284: 151: 138: 1162:{\displaystyle \nabla ({\mathbf {u} }{\mathbf {u} })=\nabla \cdot .} 557: 24: 1840: 1802: 1716: 1461: 922: 232: 163: 239:
clouds and the precipitation of water from clouds, as part of the
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The advection equation for a conserved quantity described by a
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Solutions to the advection equation can be approximated using
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Numerical simulation can be aided by considering the
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that can hold or contain the quantity or substance.
1311: 49:. Unsourced material may be challenged and removed. 1335: 1161: 1046: 906: 879: 855: 775: 743: 714: 695:{\displaystyle {\mathbf {u} }\cdot \nabla \psi =0} 694: 653: 591: 544: 514: 490: 420: 341: 193:, and the transported material is described by a 1861: 491:{\displaystyle \mathbf {u} =(u_{x},u_{y},u_{z})} 235:. Advection is important for the formation of 592:{\displaystyle \nabla \cdot {\mathbf {u} }=0,} 150:. An example of advection is the transport of 1424: 1384:Finite Volume Methods for Hyperbolic Problems 926:A simulation of the advection equation where 1573:Convective available potential energy (CAPE) 1182:Distinction between advection and convection 663:In particular, if the flow is steady, then 246: 1431: 1417: 174:. In general, any substance or conserved, 294: 267:. It is derived using the scalar field's 109:Learn how and when to remove this message 1185: 921: 783:, the advection equation above becomes: 257:hyperbolic partial differential equation 1381: 1329: 1317: 1248:at each point, although accounting for 526:operator. If the flow is assumed to be 259:that governs the motion of a conserved 16:Transport of a substance by bulk motion 1862: 1361:Chebyshev and Fourier Spectral Methods 949:, where interest typically centers on 1412: 1367:. Mineola, NY: Courier Corporation. 1357: 1341: 47:adding citations to reliable sources 18: 1535:Convective condensation level (CCL) 1239: 13: 1741:Equivalent potential temperature ( 1087: 1061: 1018: 993: 832: 805: 793: 680: 639: 617: 609: 599:and the above equation reduces to 567: 509: 383: 371: 363: 14: 1916: 1593:Conditional symmetric instability 1439:Meteorological data and variables 1278:Courant–Friedrichs–Lewy condition 1171:Since skew symmetry implies only 1540:Lifting condensation level (LCL) 1138: 1118: 1098: 1076: 1069: 1033: 1026: 998: 985: 873: 842: 824: 798: 769: 737: 672: 631: 575: 538: 439: 399: 23: 1525:Cloud condensation nuclei (CCN) 34:needs additional citations for 1788:Wet-bulb potential temperature 1630:Level of free convection (LFC) 1386:. Cambridge University Press. 1207: 1198:often serves as a synonym for 1153: 1093: 1081: 1064: 1038: 1021: 485: 446: 342:{\displaystyle \psi (t,x,y,z)} 336: 312: 283:outwards from its source in a 178:quantity can be advected by a 1: 1831:Pressure-gradient force (PGF) 1753:Sea surface temperature (SST) 1588:Convective momentum transport 1351: 263:as it is advected by a known 1645:Bulk Richardson number (BRN) 1382:LeVeque, Randall J. (2002). 1263:Advection-diffusion equation 1246:probability density function 880:{\displaystyle \mathbf {a} } 776:{\displaystyle \mathbf {u} } 744:{\displaystyle \mathbf {a} } 545:{\displaystyle \mathbf {u} } 7: 1885:Equations of fluid dynamics 1849:Maximum potential intensity 1615:Free convective layer (FCL) 1578:Convective inhibition (CIN) 1255: 917: 755:) is being advected by the 10: 1921: 1783:Wet-bulb globe temperature 1640:Maximum parcel level (MPL) 1839: 1801: 1763:Thermodynamic temperature 1697:Forest fire weather index 1653: 1563: 1510: 1444: 1685:Equivalent temperature ( 1598:Convective temperature ( 1482:Surface weather analysis 1392:10.1017/cbo9780511791253 1304: 247:Mathematical description 1732:Potential temperature ( 1477:Surface solar radiation 515:{\displaystyle \nabla } 1880:Conservation equations 1722:Relative humidity (RH) 1610:Equilibrium level (EL) 1583:Convective instability 1358:Boyd, John P. (2001). 1332:, pp. 4–6, 68–69. 1191: 1163: 1048: 942: 908: 881: 857: 777: 745: 716: 696: 655: 593: 546: 516: 492: 422: 343: 295:The advection equation 1273:Conservation equation 1218:physical oceanography 1189: 1164: 1049: 925: 909: 907:{\displaystyle \psi } 882: 858: 778: 746: 729:If a vector quantity 717: 715:{\displaystyle \psi } 697: 656: 594: 547: 517: 493: 423: 344: 265:velocity vector field 217:physical oceanography 1875:Atmospheric dynamics 1811:Atmospheric pressure 1778:Wet-bulb temperature 1680:Dry-bulb temperature 1675:Dew point depression 1058: 968: 898: 869: 787: 765: 733: 722:is constant along a 706: 667: 603: 564: 534: 506: 435: 357: 306: 43:improve this article 1905:Transport phenomena 1773:Virtual temperature 1758:Temperature anomaly 1452:Adiabatic processes 1268:Atmosphere of Earth 1252:is more difficult. 351:continuity equation 199:molecular diffusion 146:properties such as 1545:Precipitable water 1288:Overshoot (signal) 1234:hydrological cycle 1192: 1159: 1044: 1016: 981: 964:form of advection 943: 904: 877: 853: 773: 741: 712: 692: 651: 589: 542: 512: 488: 418: 349:is expressed by a 339: 253:advection equation 241:hydrological cycle 1857: 1856: 1826:Pressure gradient 1635:Lifted index (LI) 1401:978-0-521-81087-6 1230:orographic clouds 1015: 980: 947:numerical methods 812: 702:which shows that 624: 378: 275:, and taking the 255:is a first-order 119: 118: 111: 93: 1912: 1433: 1426: 1419: 1410: 1409: 1405: 1378: 1366: 1345: 1339: 1333: 1327: 1321: 1315: 1240:Other quantities 1168: 1166: 1165: 1160: 1152: 1151: 1142: 1141: 1132: 1131: 1122: 1121: 1112: 1111: 1102: 1101: 1080: 1079: 1073: 1072: 1053: 1051: 1050: 1045: 1037: 1036: 1030: 1029: 1017: 1008: 1002: 1001: 989: 988: 982: 973: 940: 913: 911: 910: 905: 886: 884: 883: 878: 876: 862: 860: 859: 854: 846: 845: 839: 835: 828: 827: 813: 811: 803: 802: 801: 791: 782: 780: 779: 774: 772: 750: 748: 747: 742: 740: 721: 719: 718: 713: 701: 699: 698: 693: 676: 675: 660: 658: 657: 652: 635: 634: 625: 623: 615: 607: 598: 596: 595: 590: 579: 578: 551: 549: 548: 543: 541: 521: 519: 518: 513: 497: 495: 494: 489: 484: 483: 471: 470: 458: 457: 442: 427: 425: 424: 419: 408: 404: 403: 402: 379: 377: 369: 361: 348: 346: 345: 340: 271:, together with 269:conservation law 227:, humidity (see 121:In the field of 114: 107: 103: 100: 94: 92: 51: 27: 19: 1920: 1919: 1915: 1914: 1913: 1911: 1910: 1909: 1870:Vector calculus 1860: 1859: 1858: 1853: 1835: 1797: 1747: 1691: 1669: 1649: 1604: 1559: 1506: 1440: 1437: 1402: 1375: 1364: 1354: 1349: 1348: 1340: 1336: 1328: 1324: 1316: 1312: 1307: 1302: 1258: 1242: 1210: 1184: 1147: 1143: 1137: 1136: 1127: 1123: 1117: 1116: 1107: 1103: 1097: 1096: 1075: 1074: 1068: 1067: 1059: 1056: 1055: 1032: 1031: 1025: 1024: 1006: 997: 996: 984: 983: 971: 969: 966: 965: 927: 920: 899: 896: 895: 891:instead of the 872: 870: 867: 866: 841: 840: 823: 822: 821: 817: 804: 797: 796: 792: 790: 788: 785: 784: 768: 766: 763: 762: 736: 734: 731: 730: 707: 704: 703: 671: 670: 668: 665: 664: 630: 629: 616: 608: 606: 604: 601: 600: 574: 573: 565: 562: 561: 556:, that is, the 537: 535: 532: 531: 507: 504: 503: 479: 475: 466: 462: 453: 449: 438: 436: 433: 432: 398: 397: 393: 389: 370: 362: 360: 358: 355: 354: 307: 304: 303: 297: 273:Gauss's theorem 249: 115: 104: 98: 95: 52: 50: 40: 28: 17: 12: 11: 5: 1918: 1908: 1907: 1902: 1897: 1892: 1887: 1882: 1877: 1872: 1855: 1854: 1852: 1851: 1845: 1843: 1837: 1836: 1834: 1833: 1828: 1823: 1818: 1813: 1807: 1805: 1799: 1798: 1796: 1795: 1790: 1785: 1780: 1775: 1770: 1768:Vapor pressure 1765: 1760: 1755: 1750: 1745: 1738: 1729: 1724: 1719: 1714: 1709: 1704: 1699: 1694: 1689: 1682: 1677: 1672: 1667: 1659: 1657: 1651: 1650: 1648: 1647: 1642: 1637: 1632: 1627: 1622: 1617: 1612: 1607: 1602: 1595: 1590: 1585: 1580: 1575: 1569: 1567: 1561: 1560: 1558: 1557: 1552: 1547: 1542: 1537: 1532: 1527: 1522: 1516: 1514: 1508: 1507: 1505: 1504: 1499: 1494: 1489: 1484: 1479: 1474: 1469: 1464: 1459: 1454: 1448: 1446: 1442: 1441: 1436: 1435: 1428: 1421: 1413: 1407: 1406: 1400: 1379: 1373: 1353: 1350: 1347: 1346: 1344:, p. 213. 1334: 1322: 1309: 1308: 1306: 1303: 1301: 1300: 1295: 1290: 1285: 1283:Kinematic wave 1280: 1275: 1270: 1265: 1259: 1257: 1254: 1241: 1238: 1209: 1206: 1183: 1180: 1158: 1155: 1150: 1146: 1140: 1135: 1130: 1126: 1120: 1115: 1110: 1106: 1100: 1095: 1092: 1089: 1086: 1083: 1078: 1071: 1066: 1063: 1043: 1040: 1035: 1028: 1023: 1020: 1014: 1011: 1005: 1000: 995: 992: 987: 979: 976: 962:skew-symmetric 941:is solenoidal. 919: 916: 903: 875: 852: 849: 844: 838: 834: 831: 826: 820: 816: 810: 807: 800: 795: 771: 760:velocity field 753:magnetic field 739: 711: 691: 688: 685: 682: 679: 674: 650: 647: 644: 641: 638: 633: 628: 622: 619: 614: 611: 588: 585: 582: 577: 572: 569: 540: 528:incompressible 511: 487: 482: 478: 474: 469: 465: 461: 456: 452: 448: 445: 441: 417: 414: 411: 407: 401: 396: 392: 388: 385: 382: 376: 373: 368: 365: 338: 335: 332: 329: 326: 323: 320: 317: 314: 311: 296: 293: 248: 245: 187:mathematically 131:earth sciences 117: 116: 31: 29: 22: 15: 9: 6: 4: 3: 2: 1917: 1906: 1903: 1901: 1900:Heat transfer 1898: 1896: 1893: 1891: 1888: 1886: 1883: 1881: 1878: 1876: 1873: 1871: 1868: 1867: 1865: 1850: 1847: 1846: 1844: 1842: 1838: 1832: 1829: 1827: 1824: 1822: 1821:Barotropicity 1819: 1817: 1814: 1812: 1809: 1808: 1806: 1804: 1800: 1794: 1791: 1789: 1786: 1784: 1781: 1779: 1776: 1774: 1771: 1769: 1766: 1764: 1761: 1759: 1756: 1754: 1751: 1749: 1744: 1739: 1737: 1735: 1730: 1728: 1725: 1723: 1720: 1718: 1715: 1713: 1710: 1708: 1705: 1703: 1700: 1698: 1695: 1693: 1688: 1683: 1681: 1678: 1676: 1673: 1671: 1666: 1661: 1660: 1658: 1656: 1652: 1646: 1643: 1641: 1638: 1636: 1633: 1631: 1628: 1626: 1623: 1621: 1618: 1616: 1613: 1611: 1608: 1606: 1601: 1596: 1594: 1591: 1589: 1586: 1584: 1581: 1579: 1576: 1574: 1571: 1570: 1568: 1566: 1562: 1556: 1553: 1551: 1550:Precipitation 1548: 1546: 1543: 1541: 1538: 1536: 1533: 1531: 1528: 1526: 1523: 1521: 1518: 1517: 1515: 1513: 1509: 1503: 1500: 1498: 1495: 1493: 1490: 1488: 1485: 1483: 1480: 1478: 1475: 1473: 1470: 1468: 1465: 1463: 1460: 1458: 1455: 1453: 1450: 1449: 1447: 1443: 1434: 1429: 1427: 1422: 1420: 1415: 1414: 1411: 1403: 1397: 1393: 1389: 1385: 1380: 1376: 1374:0-486-41183-4 1370: 1363: 1362: 1356: 1355: 1343: 1338: 1331: 1326: 1319: 1314: 1310: 1299: 1296: 1294: 1293:PĂ©clet number 1291: 1289: 1286: 1284: 1281: 1279: 1276: 1274: 1271: 1269: 1266: 1264: 1261: 1260: 1253: 1251: 1247: 1237: 1235: 1231: 1227: 1223: 1219: 1215: 1205: 1203: 1202: 1197: 1188: 1179: 1177: 1174: 1169: 1156: 1148: 1144: 1133: 1128: 1124: 1113: 1108: 1104: 1090: 1084: 1041: 1012: 1009: 1003: 990: 977: 974: 963: 958: 956: 955:CFL condition 952: 951:discontinuous 948: 938: 934: 930: 924: 915: 901: 894: 890: 863: 850: 847: 836: 829: 818: 814: 808: 761: 758: 754: 727: 725: 709: 689: 686: 683: 677: 661: 648: 645: 642: 636: 626: 620: 612: 586: 583: 580: 570: 559: 555: 529: 525: 501: 500:flow velocity 480: 476: 472: 467: 463: 459: 454: 450: 443: 431: 415: 412: 409: 405: 394: 390: 386: 380: 374: 366: 352: 333: 330: 327: 324: 321: 318: 315: 309: 302: 292: 290: 286: 280: 278: 277:infinitesimal 274: 270: 266: 262: 258: 254: 244: 242: 238: 234: 230: 226: 222: 218: 214: 209: 207: 202: 200: 196: 192: 188: 183: 181: 177: 173: 169: 165: 161: 157: 153: 149: 145: 140: 136: 132: 128: 124: 113: 110: 102: 91: 88: 84: 81: 77: 74: 70: 67: 63: 60: â€“  59: 55: 54:Find sources: 48: 44: 38: 37: 32:This article 30: 26: 21: 20: 1890:Oceanography 1742: 1733: 1727:Mixing ratio 1702:Haines Index 1686: 1664: 1599: 1512:Condensation 1456: 1383: 1360: 1337: 1330:LeVeque 2002 1325: 1320:, p. 1. 1318:LeVeque 2002 1313: 1243: 1211: 1199: 1195: 1193: 1170: 959: 944: 936: 932: 928: 893:scalar field 889:vector field 864: 728: 662: 430:vector field 301:scalar field 298: 281: 261:scalar field 252: 250: 210: 203: 195:scalar field 191:vector field 184: 134: 120: 105: 96: 86: 79: 72: 65: 53: 41:Please help 36:verification 33: 1816:Baroclinity 1663:Dew point ( 1655:Temperature 1555:Water vapor 1214:meteorology 1208:Meteorology 1176:eigenvalues 751:(such as a 213:meteorology 127:engineering 58:"Advection" 1895:Convection 1864:Categories 1793:Wind chill 1707:Heat index 1565:Convection 1502:Wind shear 1487:Visibility 1467:Lapse rate 1352:References 1224:, such as 1201:convection 757:solenoidal 724:streamline 558:divergence 554:solenoidal 289:convection 237:orographic 223:, such as 206:convection 152:pollutants 69:newspapers 1492:Vorticity 1472:Lightning 1457:Advection 1342:Boyd 2001 1298:Radiation 1250:diffusion 1196:advection 1194:The term 1173:imaginary 1091:⋅ 1088:∇ 1062:∇ 1019:∇ 994:∇ 991:⋅ 902:ψ 833:∇ 830:⋅ 806:∂ 794:∂ 710:ψ 684:ψ 681:∇ 678:⋅ 643:ψ 640:∇ 637:⋅ 618:∂ 613:ψ 610:∂ 571:⋅ 568:∇ 560:is zero: 510:∇ 395:ψ 387:⋅ 384:∇ 372:∂ 367:ψ 364:∂ 310:ψ 285:diffusive 176:extensive 144:conserved 139:transport 135:advection 1841:Velocity 1803:Pressure 1717:Humidity 1620:Helicity 1462:Buoyancy 1256:See also 918:Solution 233:salinity 229:moisture 164:enthalpy 99:May 2022 1712:Humidex 1625:K Index 1445:General 931:= (sin 522:is the 498:is the 279:limit. 137:is the 123:physics 83:scholar 1398:  1371:  1054:where 935:, cos 865:Here, 428:where 148:energy 129:, and 85:  78:  71:  64:  56:  1520:Cloud 1365:(PDF) 1305:Notes 1222:ocean 887:is a 530:then 231:) or 221:ocean 189:as a 180:fluid 168:water 160:river 158:in a 90:JSTOR 76:books 1497:Wind 1396:ISBN 1369:ISBN 1226:heat 1216:and 957:). 502:and 251:The 225:heat 215:and 156:silt 62:news 1530:Fog 1388:doi 1212:In 726:. 552:is 524:del 211:In 172:air 170:or 154:or 45:by 1866:: 1394:. 1236:. 914:. 851:0. 353:: 291:. 243:. 201:. 133:, 125:, 1748:) 1746:e 1743:θ 1736:) 1734:θ 1692:) 1690:e 1687:T 1670:) 1668:d 1665:T 1605:) 1603:c 1600:T 1432:e 1425:t 1418:v 1404:. 1390:: 1377:. 1157:. 1154:] 1149:z 1145:u 1139:u 1134:, 1129:y 1125:u 1119:u 1114:, 1109:x 1105:u 1099:u 1094:[ 1085:= 1082:) 1077:u 1070:u 1065:( 1042:, 1039:) 1034:u 1027:u 1022:( 1013:2 1010:1 1004:+ 999:u 986:u 978:2 975:1 939:) 937:t 933:t 929:u 874:a 848:= 843:a 837:) 825:u 819:( 815:+ 809:t 799:a 770:u 738:a 690:0 687:= 673:u 649:0 646:= 632:u 627:+ 621:t 587:, 584:0 581:= 576:u 539:u 486:) 481:z 477:u 473:, 468:y 464:u 460:, 455:x 451:u 447:( 444:= 440:u 416:, 413:0 410:= 406:) 400:u 391:( 381:+ 375:t 337:) 334:z 331:, 328:y 325:, 322:x 319:, 316:t 313:( 112:) 106:( 101:) 97:( 87:· 80:· 73:· 66:· 39:.

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