Apprasial of flow simulation by the Lattice Boltzmann Method

This research project presents an overview of the Lattice Boltzmann Method (LBM), an alternative numerical approach to conventional CFD. LBM has increased in popularity among the scientific community in recent years, due to its promising abilities. Namely, it claims to achieve the same level of accuracy as that of traditional CFD, while offering new benefits such as easy parallelization and the possibility of implementing complex and multiscale flows. Unlike conventional CFD which focuses on the numerical solution of the Navier Stokes Equations, the Lattice Boltzmann Method focuses on microscopic particle interactions to represent the macroscopic behaviour of the fluid. The aim of this project is to appraise the ability of the Lattice Boltzmann Method to accurately simulate incompressible flows and to analyse its accuracy performance and stability. This report presents the theoretical basis of this novel method, as well as a verification of its convergence results through some examples. These examples are implemented through an open-source code (Palabos). This project not only focuses on matching the LBM solutions with analytical or existing solutions, but it also focuses on studying the effect that the parameters of the model have on the results provided, on stability and on computational cost. The results and their analysis show that LBM is an accurate method for representing incompressible flows. The report also describes how to implement the Lattice Boltzmann Method and suggests some ways to continue the work further.Outgoin

Sudden Stops, the Real Exchange Rate, and Fiscal Sustainability: Argentina's Lessons

We offer an alternative explanation for the fall of Argentina's Convertibility Program based on the country's vulnerability to Sudden Stops in capital flows. Sudden Stops are typically accompanied by a substantial increase in the real exchange rate that breaks havoc in countries that are heavily dollarized in their liabilities, turning otherwise sustainable fiscal and corporate sector positions into unsustainable ones. In particular, we stress that the required change in relative prices is larger the more closed an economy is in terms of its supply of tradable goods. By contrasting Argentina's performance relative to other Latin American countries that were also subject to the Sudden Stop triggered by the Russian crisis of 1998, we identify key vulnerability indicators that separated Argentina from its piers. We also provide an explanation for the political maelstrom that ensued after the Sudden Stop, based on a War of Attrition argument related to the wealth redistribution conflict triggered by the Sudden Stop and fiscal collapse. This framework also provides elements to rationalize the banking crisis that accompanied the fall of Convertibility.

Phoenix Miracles in Emerging Markets: Recovering without Credit from Systemic Financial Crises

Using a sample of emerging markets that are integrated into global bond markets, we analyze the collapse and recovery phase of output collapses that coincide with systemic sudden stops, defined as periods of skyrocketing aggregate bond spreads and large capital flow reversals. Our findings indicate the presence of a very similar pattern across different episodes: output recovers with virtually no recovery in either domestic or foreign credit, a phenomenon that we call a Phoenix Miracle, where output rises from its ashes, suggesting that firms go through a process of financial engineering to restore liquidity outside formal credit markets. Moreover, we show that the U. S. Great Depression could be catalogued as a Phoenix Miracle. However, in contrast to the U. S. Great Depression, EM output collapses occur in a context of accelerating price inflation and falling real wages, casting doubt on price deflation and nominal wage rigidity as key elements in explaining output collapse, and suggesting that financial factors figure prominently in these collapses.

Iphone Book

The iPhone is a line of Internet- and multimedia-enabled smartphones designed and marketed by Apple Inc. The first iPhone was unveiled by Apple CEO Steve Jobs on January 9, 2007, and released on June 29, 2007. An iPhone can function as a video camera (video recording was not a standard feature until the iPhone 3GS was released), a camera phone, can send texts and receive visual voicemail, a portable media player, and an Internet client with email and web browsing capabilities, and both Wi-Fi and 3G connectivity. The user interface is built around the device's multi-touch screen, including a virtual keyboard rather than a physical one. Third-party as well as Apple application software is available from the App Store, which launched in mid-2008 and now has over 350,000 "apps" approved by Apple. These apps have diverse functionalities, including games, reference, GPS navigation, social networking, e-booksEscuela Técnica Superior de Ingeniería de TelecomunicaciónUniversidad Politécnica de Cartagen

Phoenix Miracles in Emerging Markets: Recovering without Credit from Systemic Financial Crises

Using a sample of emerging markets that are integrated into global bond markets, we analyze the collapse and recovery phase of output collapses that coincide with systemic sudden stops, defined as periods of skyrocketing aggregate bond spreads and large capital flow reversals. Our findings indicate the presence of a very similar pattern across different episodes: output recovers with virtually no recovery in either domestic or foreign credit, a phenomenon that we call Phoenix Miracle, where output %u201Crises from its ashes%u201D, suggesting that firms go through a process of financial engineering to restore liquidity outside the formal credit markets. Moreover, we show that the US Great Depression could be catalogued as a Phoenix Miracle. However, in contrast to the US Great Depression, EM output collapses occur in a context of accelerating price inflation and falling real wages, casting doubts on price deflation and nominal wage rigidity as key elements in explaining output collapse, and suggesting that financial factors are prominent for understanding these collapses.

Paradas repentinas, tipo de cambio real y viabilidad fiscal: enseñanzas de Argentina

(Disponible en idioma inglés únicamente) Presentamos una explicación alternativa de la caída del programa de convertibilidad de Argentina, basándonos en la vulnerabilidad del país a las paradas repentinas de los flujos de capitales. Las paradas repentinas por lo general van acompañadas de un incremento considerable del tipo de cambio real, lo que provoca el caos en países con pasivos considerablemente dolarizados y hace insostenibles posiciones fiscales y del sector privado por lo demás sostenibles. Subrayamos en particular que la variación necesaria de los precios relativos es mayor mientras más cerrada sea una economía en términos de su oferta de bienes transables. Al contrastar el desempeño de Argentina con el de otros países latinoamericanos que también estuvieron sometidos a la parada repentina provocada por la crisis de Rusia en 1998, identificamos indicadores claves de vulnerabilidad que distinguieron a Argentina de sus pares. También ofrecemos una explicación del torbellino político que se produjo a continuación de la parada repentina, basándonos en un argumento de guerra de desgaste y colapso fiscal. Este marco también aporta elementos para racionalizar la crisis bancaria que acompañó la caída de la convertibilidad.

On the Empirics of Sudden Stops: The Relevance of Balance-Sheet Effects

Using a sample of 32 developed and developing countries we analyze the empirical characteristics of Sudden Stops in capital flows and the relevance of balance-sheet effects in the likelihood of their occurrence. We find that large real exchange rate (RER) fluctuations accompanied by Sudden Stops are basically an emerging market (EM) phenomenon. Sudden Stops seem to come in bunches, grouping together countries that are different in many respects. However, countries are similar in that they remain vulnerable to large RER fluctuations. This may be the case because countries are forced to make large adjustments in the absorption of tradable goods, and/or because the size of dollar liabilities in the banking system (i. e. , domestic liability dollarization, or DLD) is large. Openness, understood as a large supply of tradable goods that reduces leverage over the current account deficit, in combination with DLD, is a key determinant of the probability of Sudden Stops. The relationship between Openness and DLD in the determination of the probability of Sudden Stops is highly non-linear, implying that the interaction of high current account leverage and high dollarization may be a dangerous cocktail.

Relative Price Volatility Under Sudden Stops: The Relevance of Balance Sheet Effects

Sudden Stops are associated with increased volatility in relative prices. We introduce a model based on information acquisition to rationalize this increased volatility. An empirical analysis of the conditional variance of the wholesale price to consumer price ratio using panel ARCH techniques confirms the relevance of Sudden Stops and potential balance-sheet effects as key determinants of relative-price volatility, where balance-sheet effects are captured by the interaction of a proxy for potential changes in the real exchange rate (linked to the degree of external leverage of the absorption of tradable goods) and a measure of domestic liability dollarization.

Systemic Sudden Stops: The Relevance of Balance-Sheet Effects and Financial Integration

Using a sample of 110 developed and developing countries for the period 1990-2004, this paper analyzes the characteristics of systemic sudden stops (3S) in capital flows and the relevance of balance-sheet effects in the likelihood of their materialization. A small supply of tradable goods relative to their domestic absorption?a proxy for potential changes in the real exchange rate?and large foreign-exchange denominated debts towards the domestic banking system are claimed to be key determinants of the probability of 3S, producing a balancesheet effect with non-linear impacts on the probability of 3S. While financial integration is up to a point associated with a higher likelihood of 3S, beyond that point financial integration is associated with a lower likelihood of 3S.

On the Empirics of Sudden Stops: The Relevance of Balance-Sheet Effects

Using a sample of 32 developed and developing countries we analyze the empirical characteristics of sudden stops in capital flows and the relevance of balance sheet effects in the likelihood of their materialization. We find that large real exchange rate (RER) fluctuations coming hand in hand with Sudden Stops are basically an emerging market (EM) phenomenon. Sudden Stops seem to come in bunches, grouping together countries that are different in many respects. However, countries are similar in that they remain vulnerable to large RER fluctuations – be it because they could be forced to large adjustments in the absorption of tradable goods, and/or because the size of dollar liabilities in the banking system (i.e., domestic liability dollarization, or DLD) is high. Openness, understood as a large supply of tradable goods that reduces leverage over the current account deficit, coupled with DLD, are key determinants of the probability of Sudden Stops. The relationship between Openness and DLD in the determination of the probability of Sudden Stops is highly non-linear, implying that the interaction of high current account leverage and high dollarization may be a dangerous cocktail.